algebra
posted by Jake on .
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(25NC)=8
.5*NC6.25+.25*NC=8
solve for NC