Amixture of 30 pounds of candy sells for $1.10 a pound. the mixture consists of chocolates worth $1.50 a pound and chocolates worth 90¢ a pound. how many pounds of the $1.50 chocolate were used to make the mixture?

if x represents the pounds of $1.50 chocolates used, then which of the following represents the pounds of 90¢ chocolates used?
x
30 - x
30