Use composition to show that f(x) and the equation f(x) -2x+10 are inverse

Match each equation with the operation you can use to solve for the variable. 1 subtract 10 2 divide by 10 3add 18 4add 10 5 subtact 18 6multiply by 5. 7multiply by 10. a 5 = 10p b p + 10 = 18 c p + 18 = 5 d 5p = 10

The sum of two numbers is 12 and their difference is 18 what are the two numbers

Nine more than four times a number is the same as one less than twice the number. find the number?