单项选择题
If the radius of a circular region were decreased by 20 percent, the area of the circular region would decrease by what percent（）
A. 16% B. 20% C. 36% D. 40% E. 44%
单项选择题 The median salary for professional group A is $40,610. The median salary for professsional group Bis $40,810. The median salary for groups A and $ 40,710 B combined（）
单项选择题 （）
单项选择题 a and b are positive integers（）
