## Step 1: Define the symbolic representation of the problem
The problem involves maximizing an objective function subject to several constraints. The variables are 'steaks', 'milkshakes', 'black beans', and 'chicken thighs', which we can denote as $x_0, x_1, x_2, x_3$ respectively.

## Step 2: Translate the objective function into symbolic notation
The objective function to maximize is $2.74x_0 + 5.05x_1 + 4.98x_2 + 6.54x_3$.

## 3: List the constraints in symbolic notation
1. $5x_0 + 4x_1 + 5x_2 + 2x_3 \leq 114$ (iron constraint)
2. $4x_0 + 3x_1 + x_2 + 9x_3 \leq 71$ (carbohydrates constraint)
3. $5x_0 + 4x_1 \geq 24$ (iron from steaks and milkshakes)
4. $5x_0 + 2x_3 \geq 11$ (iron from steaks and chicken thighs)
5. $x_2 + 9x_3 \geq 14$ (carbohydrates from black beans and chicken thighs)
6. $3x_1 + 9x_3 \geq 16$ (carbohydrates from milkshakes and chicken thighs)
7. $4x_0 + 9x_3 \geq 15$ (carbohydrates from steaks and chicken thighs)
8. $3x_1 + x_2 \geq 12$ (carbohydrates from milkshakes and black beans)
9. $4x_0 + 3x_1 + x_2 \geq 16$ (carbohydrates from steaks, milkshakes, and black beans)
10. $4x_0 + 3x_1 + 9x_3 \geq 16$ (carbohydrates from steaks, milkshakes, and chicken thighs)
11. $3x_1 + x_2 + 9x_3 \geq 16$ (carbohydrates from milkshakes, black beans, and chicken thighs)
12. $4x_0 + 3x_1 + x_2 \geq 10$ (carbohydrates from steaks, milkshakes, and black beans)
13. $4x_0 + 3x_1 + 9x_3 \geq 10$ (carbohydrates from steaks, milkshakes, and chicken thighs)
14. $3x_1 + x_2 + 9x_3 \geq 10$ (carbohydrates from milkshakes, black beans, and chicken thighs)
15. $5x_0 + 5x_2 \leq 69$ (iron from steaks and black beans)
16. $4x_1 + 5x_2 \leq 66$ (iron from milkshakes and black beans)
17. $5x_0 + 2x_3 \leq 64$ (iron from steaks and chicken thighs)
18. $5x_0 + 4x_1 \leq 87$ (iron from steaks and milkshakes)
19. $5x_0 + 4x_1 + 2x_3 \leq 34$ (iron from steaks, milkshakes, and chicken thighs)
20. $5x_0 + 4x_1 + 5x_2 \leq 68$ (iron from steaks, milkshakes, and black beans)
21. $5x_0 + 5x_2 + 2x_3 \leq 58$ (iron from steaks, black beans, and chicken thighs)
22. $5x_0 + 4x_1 + 5x_2 + 2x_3 \leq 58$ (iron from all sources)
23. $3x_1 + 9x_3 \leq 67$ (carbohydrates from milkshakes and chicken thighs)
24. $4x_0 + 9x_3 \leq 20$ (carbohydrates from steaks and chicken thighs)
25. $4x_0 + 3x_1 \leq 62$ (carbohydrates from steaks and milkshakes)
26. $3x_1 + x_2 \leq 70$ (carbohydrates from milkshakes and black beans)
27. $4x_0 + 3x_1 + x_2 + 9x_3 \leq 70$ (carbohydrates from all sources)

## 4: Define the symbolic representation
```json
{
    'sym_variables': [
        ('x0', 'steaks'),
        ('x1', 'milkshakes'),
        ('x2', 'black beans'),
        ('x3', 'chicken thighs')
    ],
    'objective_function': '2.74*x0 + 5.05*x1 + 4.98*x2 + 6.54*x3',
    'constraints': [
        '5*x0 + 4*x1 + 5*x2 + 2*x3 <= 114',
        '4*x0 + 3*x1 + x2 + 9*x3 <= 71',
        '5*x0 + 4*x1 >= 24',
        '5*x0 + 2*x3 >= 11',
        'x2 + 9*x3 >= 14',
        '3*x1 + 9*x3 >= 16',
        '4*x0 + 9*x3 >= 15',
        '3*x1 + x2 >= 12',
        '4*x0 + 3*x1 + x2 >= 16',
        '4*x0 + 3*x1 + 9*x3 >= 16',
        '3*x1 + x2 + 9*x3 >= 16',
        '4*x0 + 3*x1 + x2 >= 10',
        '4*x0 + 3*x1 + 9*x3 >= 10',
        '3*x1 + x2 + 9*x3 >= 10',
        '5*x0 + 5*x2 <= 69',
        '4*x1 + 5*x2 <= 66',
        '5*x0 + 2*x3 <= 64',
        '5*x0 + 4*x1 <= 87',
        '5*x0 + 4*x1 + 2*x3 <= 34',
        '5*x0 + 4*x1 + 5*x2 <= 68',
        '5*x0 + 5*x2 + 2*x3 <= 58',
        '5*x0 + 4*x1 + 5*x2 + 2*x3 <= 58',
        '3*x1 + 9*x3 <= 67',
        '4*x0 + 9*x3 <= 20',
        '4*x0 + 3*x1 <= 62',
        '3*x1 + x2 <= 70',
        '4*x0 + 3*x1 + x2 + 9*x3 <= 70'
    ]
}
```

## 5: Write the Gurobi code
```python
import gurobi

# Create a new model
m = gurobi.Model()

# Define the variables
x0 = m.addVar(name='steaks', vtype=gurobi.GRB.INTEGER)
x1 = m.addVar(name='milkshakes', vtype=gurobi.GRB.INTEGER)
x2 = m.addVar(name='black beans', vtype=gurobi.GRB.INTEGER)
x3 = m.addVar(name='chicken thighs', vtype=gurobi.GRB.INTEGER)

# Objective function
m.setObjective(2.74*x0 + 5.05*x1 + 4.98*x2 + 6.54*x3, gurobi.GRB.MAXIMIZE)

# Constraints
m.addConstr(5*x0 + 4*x1 + 5*x2 + 2*x3 <= 114)
m.addConstr(4*x0 + 3*x1 + x2 + 9*x3 <= 71)
m.addConstr(5*x0 + 4*x1 >= 24)
m.addConstr(5*x0 + 2*x3 >= 11)
m.addConstr(x2 + 9*x3 >= 14)
m.addConstr(3*x1 + 9*x3 >= 16)
m.addConstr(4*x0 + 9*x3 >= 15)
m.addConstr(3*x1 + x2 >= 12)
m.addConstr(4*x0 + 3*x1 + x2 >= 16)
m.addConstr(4*x0 + 3*x1 + 9*x3 >= 16)
m.addConstr(3*x1 + x2 + 9*x3 >= 16)
m.addConstr(4*x0 + 3*x1 + x2 >= 10)
m.addConstr(4*x0 + 3*x1 + 9*x3 >= 10)
m.addConstr(3*x1 + x2 + 9*x3 >= 10)
m.addConstr(5*x0 + 5*x2 <= 69)
m.addConstr(4*x1 + 5*x2 <= 66)
m.addConstr(5*x0 + 2*x3 <= 64)
m.addConstr(5*x0 + 4*x1 <= 87)
m.addConstr(5*x0 + 4*x1 + 2*x3 <= 34)
m.addConstr(5*x0 + 4*x1 + 5*x2 <= 68)
m.addConstr(5*x0 + 5*x2 + 2*x3 <= 58)
m.addConstr(5*x0 + 4*x1 + 5*x2 + 2*x3 <= 58)
m.addConstr(3*x1 + 9*x3 <= 67)
m.addConstr(4*x0 + 9*x3 <= 20)
m.addConstr(4*x0 + 3*x1 <= 62)
m.addConstr(3*x1 + x2 <= 70)
m.addConstr(4*x0 + 3*x1 + x2 + 9*x3 <= 70)

# Solve the model
m.optimize()

# Print the solution
if m.status == gurobi.GRB.OPTIMAL:
    print('Objective: ', m.objVal)
    print('Steaks: ', x0.varValue)
    print('Milkshakes: ', x1.varValue)
    print('Black beans: ', x2.varValue)
    print('Chicken thighs: ', x3.varValue)
else:
    print('No optimal solution found')
```