Average is just the total divided by the number of things you added up.
You've been given 4 numbers.
So just add 7.75+7.25+7.33+7.6 and then divide that by 4.
the answer is therefore 29.93/4
=7.4285
You can check if that seems right by just looking at the numbers, the average will be inbetween the smallest and largest numbers, so it matches up.