(3a^4 * b^-2) * (2a^7 * b^-1)
= 6*a^(4+7)*b^(-2-1)
= 6*a^11*b^-3
36 inches because 12,24,36 and 18,36, 36=36
3, 6, 12
I guessed and checked. So if 3 is the smallest number, I would, multiply it by 3, which is 9. 9 is 3 less than the largest number which would be 12. 12 + 3 is 15. To find the third number, subtract 21 and 15 which is 6