To get the new bench price, you multiply 50 × 0.2, which gets you 10, then you subtract 50-10, which is 40, and $40 is the price of the bench on sale. (You could also do 50 × 0.8 to avoid a step and still get the same answer).
You then take 40 and multiply is by 0.05 to get the tax, which would be $2. From here, you add 40+2 to get $42, the amount of money Presley paid for the bench.
