If the first 10 bricks come out at $ 4.5, I would be spending $ 45. The other 10 bricks come out at $ 3.5 so he would be spending $ 35. Therefore, he has $ 20 available to buy bricks at $ 2.5, which would be buying 8 additional bricks. Thus, in total, with $ 100, 28 bricks were purchased.
