D.31
To find the average, we must add all the numbers up and then divide by the amount of numbers there.
Here we have 3 numbers, which two values are given and the average.
So average A, is found by adding all number then dividing by the number of numbers added.
Let's say the average, 25 = 22+22+x/3
Combine like terms, so 25=44+x/3
Then to cancel out the three on the left we must multiply 3 on both sides. 3•25=44+x/3•3
Simplify the equation into
75=44+x
Now we subtract 44 from both sides to move it over to the left, so we can isolate the variable.
75-44=44+x-44
Simplify
31=x
The third person is D. 31