Jack's average in math for the first nine weeks was an 88. his second nine weeks average decreased 12.5% what was his average for the second nine weeks? explain how you got your answer.

Well 10% of 88= 8.8
5% then would be 4.4, so then 2.5% would be 2.2.

So it would be 10% (8.8) + 2.5% (2.2) = 10.1

So for the second nine weeks his average decreased by 12.5% (10.1) so it would be, 88-10.1= 77.9

Answer = 77.9

Hope that's correct haha