58 because 80 times 15 percent is 12. so you subtract 12 from 80 that gives you 68 then you subtract the coupon which is 10 dollars. you total is 58.
3x^2 / 4 = 48
Multiply both sides by 4 to get rid of the four on the left.
3x^2 = 192
Divide both sides by 3
x^2 = 64
The square root 64 to get x
Remember there are two answers
x = 8 and x = -8
