First you do $60 divided by 4 which equals $15
Then you take 1% of 15 which is 0.15 and multiply thirty percent by that and subtract thirty percent from 100% and get 70% which is 10.5
The best way for him to check his answer would be to simply plug in the value found for x into the equation.
4(2) - 6 = 2
8 - 6 = 2
2 = 2