3 x 25 = 75
4 x 12 = 48
75 - 10 = 65
65 + 48 = 113
Answer: 113 markers and crayons or 65 crayons and 48 markers
First term [ a ] = 6.3
Common difference [ d ] = 8.8 - 6.3 = 2.5
Using general term formula,

78.8 = 6.3 + (n-1)*2.5
2.5*(n-1) = 72.5 [ Dividing both sides by 2.5 ]
n-1 = 29
n = 30
Hence, 78.8 is the
30th term in the arithmetic series.
1/6(36 + 1/2) = 6 + 1/12 = 72/12 + 1/12 = 73/12
You would get $15 in total because 5x3=15.