Problem solving question with average

Question

Johnny had to take a test a day late. His 96 raised the class average from 71 to 72. How many students, including Johnny, took the test?

I tried to do trial and error to see how many students there were but I couldn't figure it out.

Answer 1

Hint: Letting $n$ be the number of students excluding Johnny... $$\text{Old average} = \frac{71n}{n}$$ $$\text{New average} = \frac{71n + 96}{n+1}$$

Note that $\text{New average} - \text{Old average} = 1$.