Answer:
what
Step-by-step explanation:
85
Write the numbers in order
66, 72, 74, 80, 83, 87, 91, 95, 98, 99
Find the middle number
83 and 87 are in the middle, so find the mean of them. 83+87= 170
170/2 = 85.
find the square of both numbers
13²=169
5²=25
minus the square
169-25 to get 144
find the square root of 144
✓144=12 the third side is 12
I believe it is 2 so X=2