Mr.lippman brought a dryer for $160 and sold it for $240. if the overhead expenses were 20% of the selling price, what was the rate of the profit on the selling price?

The answer would be $32 or as a rate, it'll be 8%.

    4(3x + 2) - 9 = 8x + 7
4(3x) + 4(2) - 9 = 8x + 7
      12x + 8 - 9 = 8x + 7
            12x - 1 = 8x + 7
            - 8x       - 8x      
               4x - 1 = 7
                   + 1 + 1
                     4x = 8
                      4     4
                       x = 2

The property that justifies Emily's first step is the addition property of equality (2).