The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: how many numbers are divisible by both 2 and 3 up to 300 ?
[EX A]: 50

[EX Q]: Problem: seed mixture x is 40 percent ryegrass and 60 percent bluegrass by weight ; seed mixture y is 25 percent ryegrass and 75 percent fescue . if a mixture of x and y contains 40 percent ryegrass , what percent of the weight of this mixture is x ?
[EX A]: 100 %

[EX Q]: Problem: x can finish a work in 21 days . y can finish the same work in 15 days . yworked for 10 days and left the job . how many days does x alone need to finish the remaining work ?
[EX A]:
7