Given ingredients A, B, C, D, of which we have a, b, c, d amounts, we want to find the most profiting combination, knowing that for example recipe 1 uses 2 A and 3 B, and its product sells for 300 units, recipe 2 uses 2 B and 4 C and sells for 400 units, recipe 3 uses 1 A, 2 B and 1 D, and sells...