Tom's mother pays him $.50 for each problem his gets correct on his test, but he has to give her .25 for each problem he gets wrong. If Tom makes $8.00 on the test, and there were 25 total problems on the test, how many did he answer correctly?

Thanks!

NC is number corret.

NC+NR=25

.5*NC-.25NW=8
.5*NC-.25(25-NC)=8
.5*NC-6.25+.25*NC=8
solve for NC