28,500 subtracted from 33,829.50 is 5,329.50. Then you divide the difference by the number of months. (5,329.50/66) . That dividend would be 80.75. sorry I could not provide further information.
If you're not sure, begin by looking for any divisor that will divide into 24a^3c and 3a without leaving a remainder. Note that 3 is such a number, and a is another.
Factoring out 3a from 24a^3*c and 3a, we get 3a{8a^2*c, 1}
