A science show preforms two different demonstrations, demonstration 1 and demonstration 2. In demonstration 1, 10 units of mint and 20 units of the active ingredient is used to make 25 units of minty foam. In demonstration 2, 12 units of mint and 15 units of the active ingredient is used to make 18 units of minty foam. In addition, demonstration 1 creates 5 units of black tar while demonstration 2 creates 3 units of black tar. The show has available 120 units of mint and 100 units of active ingredients. If at most 50 units of black tar can be produced, how many of each demonstration should be done to maximize the amount of minty foam produced?