Question 986041
The difference between the two test scores is 24.  The difference between the two averages is 3.  That would be 8 tests.  Why?
average=total/n
If the total increases by 24, it is still divided by the number of tests to get the average.  If the average is increased by 3, there has to be 24/3.
Check:
8 tests*90=720
At the moment, he has 623.
If that is the case, 623+73=696
696/8=87