Let x and y be positive integers. how much greater is the average of 9x, 24y, and 48 than the average of 6x, 18y, and 12? A) x+2y+12 B) x+2y+24 C) 2x+y+36 D) none of these

The average of the first expression is found by adding and divding by 3

= (9x + 24y + 48) / 3 = 3x + 8y + 16

also average for second one = (6x + 18y + 12) / 3 = 2x + 6y + 4

so answer is 3x + 8y + 16 - (2x + 6y + 4) = x + 2y + 12

Option A