Could i get some to evaluate -a- (−8)+b where a =2 and b = -7

Graph the system: f(x)= 3/x-2; f(x)= 1/2x + 2

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *