Plz give me explanation how to solve

120 people who all need 1 drink, so if each drink needs .5 cups of concentrate you will do 120d × 0.5 = 60 total cups of concentrate. if you then set up a fraction, you could cross multiply to get the answer, but I cant do fractions here so I'll say this: if every 5 cups of concentrate gives 19 cups of water, then you divide 60 cups by 5 cups to see how many "batches" of this recipie you will need, you get 12 batches, so 12 x 19 (cups of water per batch) to get 218 ( I think, check my math with a calculator