A navy ship is stocking food onto their submarine and their staff can eat either a salad or fruit bowl for their fibre and vitamin intake. The nutritionist in charge of this voyage needs to ensure that their staff gets at least 90 units of vitamin and 110 units of fibre each. Each salad contains 7 units of vitamins and 12 units of fibre. Each fruit bowl contains 15 units of vitamin and 3 units of fibre. In addition, since fruit bowls take longer to prepare, at most 30% of their meals should be fruit bowls. If each salad contains 2 units of potassium and each fruit bowl contains 8 units of potassium, how many of each should they prepare for each staff to maximize their potassium intake?