Question

A recipe for sparkling grape juice calls for 1 1/2 quarts of sparkling water and 3/4 quart of grape juice, how much sparkling water would you need to mix with 9 quarts of grape juice?

Answer 1

For this case we can make the following rule of three:
 1 1/2 ---------> 3/4
 x --------------> 9
 We clear the value of x:
 x = ((9) / (3/4)) * (1 1/2)
 Rewriting we have:
 x = ((9) * (4/3)) * (1 1/2)
 x = (36/3) * (1 1/2)
 x = (12) * (1 1/2)
 x = (12) * (3/2)
 x = 18
 Answer:
 you would need 18 quarts of sparkling water to mix with 9 quarts of grape juice