Question

How can I get the average?

Answer 1

The average is pretty simple to find. Add up all the numbers, then divide by how many numbers there are. In other words it is the sum divided by the count.

The answer to this specific question can be modeled as $\frac{72+76+x}{3}\geq 75$.  After simplifying everything, you would get x $\geq$ 77, so Justin has to get at least a 77 to get a 75 average.