Question 1044322
average = total/n
let average for 7 months =x
then x=total/7
when there are 8 months, the average is increased by 25 and the total increased by 1275, because that is what he earned.
so  (x+25)=(total+1275)/8
7x=total; 8x=(8/7) total
8x+200=total +1275
8x=total+1075=(8/7) total
1075=(1/7) total, because (8/7) total-1 total =(1/7) total
total=$7525, and that is for 7 months
average for 7 months is $1075/month
total for 8 months is $8800, adding $1275.
average for 8 months is $8800/8=$1100, and that is $25 more than the 7 month average.
The answer is $1100 average monthly income for the first 8 months of the year