SOLUTION: Mariana averaged 83 on her first three history exams . The first score was 90. The second score was 3 less that then third score. What did she score on the second and third exams ?

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Question 1037987: Mariana averaged 83 on her first three history exams . The first score was 90. The second score was 3 less that then third score. What did she score on the second and third exams ?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
So the average was,
A=%2890%2BX%2BY%29%2F3=83
and
X=Y-3
Substituting,
%2890%2BY-3%2BY%29%2F3=83
87%2B2Y=249
2Y=162
Y=81
So then,
X=81-3
X=78
So her test scores are 90,78, and 81.