单选题
If a is increased by 10% and b is decreased by 10%, the resulting numbers will be equal. What is the ratio of a to b?
【正确答案】
A
【答案解析】a+10%(a)=a+.1a=1.1a. Also, b -10%(b) = b -.1b = .9b. Then, 1.1a = .9b, and 