Let’s say that the lemonade power is (p) and the water is (w). Let’s also say that one cup of lemonade is (L) Since you need 3 cups of (p) and 7 cups of (w) to make 1 of (L), the equation would be f(L) = 3p + 7w The (L) would be input of how many cups you need So if you need 5 cups, use 5 as your input F(5) =3(5)+7(5) 3x5=15 7x5=35 You need 15 cups of Lemonade powder And 35 cups of water