Question

John had the average score of 84 on his first three Checkpoints. The first score was 67. The second score was 7 less than the third score. What are his scores in the second and third Checkpoints?

Answer 1

\[ Let\ s_2\ and\ s_3\]
be the scores on the second and third checkpoints respectively.
The average score would be
\[ Average = \frac{s_1+s_2 + s_3}{3}\]
Since the score on the first checkpoint is 67, and the average is 84 we have:
\[84 = \frac{67 + s_2 +s_3}{3} \]
We are also given that the second score was 7 less than the third..
\[ \rightarrow s_2 = s_3-7\]

We have 2 equations and 2 unknowns. Solve for s2 and s3.