to find the cost of one cell phone, all you have to do is divide the total cost by the number of units.
you'll have:
[tex] \frac{6a^2 + 5ab - 6b^2}{3a-2b} \\ factor~the~numerator \\ \frac{6a^2+5ab-6b^2}{3a-2b} = \frac{(3a-2b)(2a+3b)}{3a-2b} \\ cancel~out~(3a-2b) \\ therefore~the~cost ~of~one~cell~phone~is~ (2a+3b)[/tex]
