考前一天问一道数学题，看了半天没看懂。。。

rockalmighty

A rectangular game board is composed of identical squares arranged in a rectangular array of e rows and r+1 columns. The r rows are numbered from 1 through r, and the r+1 columns are numbered from 1 through r+1. If r>10, which of the following represents the number of squares on the board that are neither in the 4th row nor in the 7th column? A. r^2-r B. r^2-1 C. r^2 D. r^2+1 E. r^2+r 这个题是什么意思，怎么做呀？

dingda6

一个由方块组成的r行，r+1（r>10）列的矩形，去掉第4行和第7列，还剩多少个方块？
这样讲应该很简单了吧

c5085185

A         r*(r+1)-(r+r+1-1)

古流月

thanks liao kai