This one is fairly simple. If he gets a seven percent commission and sells 3,000 dollars worth of electronics, all you need to do is find what seven percent of 3,000 is.
You see that you need a percentage. You are given the amount that she got wrong, assuming the questions are weighted the same, you divide 36 by 48. This gives you .75. Then you multiply .75 by 100% giving you 75%.
