SOLUTION: On a two part exam, Kevin answered 72% of the questions in part-A and 80% of the questions in part-B correctly. In both parts together he answered 75% of the questions correctly. I

Question 1094334: On a two part exam, Kevin answered 72% of the questions in part-A and 80% of the questions in part-B correctly. In both parts together he answered 75% of the questions correctly. If there are 30 questions in part-B, how many questions are in part-A?
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
.72a+.8b=.75(a+b)
b=30
.72a+.8*30=.75(a+30)
.72a+.8*30=.75a+.75*30
.8*30-.75*30=.75a-.72a
.05*30=.03a
5*30=3a
50=a
check
.72*50+.80*30=.75(80)
.72*50+.80*30=60
60=60
ok

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