Question 883852
To find an average simply add up all the numbers in the group and divide the result by the amount of numbers in that group.

Here you have a group of 2 numbers: 54 and 81.

To find their average you need to add them up and then divide the result by 2 (because that is amount of numbers in that group).

So... 54 + 81 = 135

135/2 = 67.5

67.5% is the average