the number of cups of red Lin needs is 27 cups
Step-by-step explanation:number of parts of red = 3
number of parts of yellow = 2
the ratio of red to yellow = 3:2
when lin's number of cups of yellow = 18
let the number of cups of red = x
3 red = 2 yellow
x red = 18 yellow
cross multiply:
3(18) = 2(x)
54 = 2x
divide both sides by 2:
54/2 = 2x/2
x = 27
Hence, the number of cups of red Lin needs is 27 cups