Question 689276
How many tests are part of the 64 average? You need to know that before you can solve.


In general the formula will be
{{{(64 * y) + x = 70*(y+1)}}} where y is the number of tests that resulted in an average of 64. And x is the next score you need in order to average 70 

So if you have taken one test and received a 64, then you will solve for the next score as follows
{{{64 + x = 70 * 2}}}
{{{x = 140 - 64}}}
{{{x = 76}}}