Question

alisha is making punch for a graduation party. The recipe requires twice as much orange juice as cranberry juice and 8 times as much ginger ale as cranberry juice. If she plans to make 165 oz of punch, how much orange juice does she need?

Answer 1

let 'o'=amount of orange juice, 'g'=amount of ginger ale and 'c'=amount of cranberry juice.
we can then write:
o = 2c
g = 8c

and the entire punch contains all three, so we can also write:
o + g + c = 165

therefore:
2c + 8c + c = 165
11c = 165
c =15 oz

therefore o=2c=2*15=30 oz