If the sum of three consecutive multiples of 9 is 108, then the average of multiples is
If x is a multiple of 9, then next multiple is x + 9
The next to this is x + 9 + 9 = x + 18
So three consecutive multiples of 9 are x, x + 9, x + 18
x + (x + 9) + (x + 18) = 108
3x + 27 = 108
x = 108−273 = 813 = 27
So, first multiple is 27
Second multiple is 27 + 9 = 36
Third multiple is 27 + 18 = 45.
Average of multiples = 27+36+453
= 36