The difference between nine times a number and seventy-two

Question

Pls answer I need help

Answer 1

generally "difference" is treated as a non-negative number, so

take the absolute value of 9x-72 = |9x-72| = 9|x-8|

= 9(x-8) when x>8

or

= 9(8-x) when x<8

if x= 8, the difference = 0