Question

Marianna average 84 on her first three history exams. The first score was 67 the second score was seven less than the third score. What did she score on the second and third exams?

Answer 1

Let S=score on the second exam, then
(67+S+(S+7))/3=84
cross multiply
2S+74=252
2S=178
S=89
So second exam: 89
third exam=89+7=96
Check: (67+89+96)/3=84 ok.