Seed mixture X is 40% ryegrass and 60% bluegrass by weight; seed mixture Y is 25% ryegrass and 75% fescue. If a mixture of X and Y contains 31% ryegrass, what percent of the weight of the mixture is from mixture X?  Select the correct option
A) 20% B) 30% C) 40% D) 50% E) 60%
31% is 6%-points above 25% and 9%-points below 40%.   Thus the ratio of mixture Y to mixture X is 3:2.   The percent of mixture X is 2/5 = 40%.   The answer is 40%.
<result>C</result>
Seed mixture X is 40% ryegrass and 60% bluegrass by weight; seed mixture Y is 25% ryegrass and 75% fescue. If a mixture of X and Y contains 31% ryegrass, what percent of the weight of the mixture is from mixture X?