review V2.31 for the prep power 第31题

If x is equal to the sum of the even integers from 40 to 60, inclusive, and y is the number of even integers from 40 to 60, inclusive, what is the value of x+y?

A: 550

B: 551

C: 560

D: 561

E: 572

正确答案为：D，

请问怎么做的？