A paint store mixes 3/4 pint of red paint and 2/3 pint of white paint to make a new paint color called Perfect Pink. How many pints of red paint would be needed to make 40 pints of Perfect Pink paint?
Choose the correct choice from the following options:  A) 9  B) 16  C) 21  D) 25 1 / 3  E) 28 1 / 2

Rationale: "3 / 4 pint is required to make 3 / 4 + 2 / 3 = 17 / 12 pint of perfect pink so 17 / 12 pint requires 3 / 4 pint of red . . 1 pint will require 3 / 4 * 12 / 17 = 9 / 17 . . 40 pints will require 9 / 17 * 40 = 21 pints . . c"
Answer: C