数学题~求助哦

momohere88

Q28:

For any positive integer n, the sum of the first n positive integers equals [n(n+1)]/2.  What is the sum of all the even integers between 99 and 301?

请各位大侠帮忙把题目翻译一下~把解法和步骤也写下哈·~小女子感激不尽