Let x tickets sold be adults, then (1024-x) were of childrens tickets, 9x+(1024-x)4 = 7680. The above equation is for total money solve it you will get x=720 hence, number of adult tickets were 720 and number of child tickets were 300 :)
When you divide by 100 you are essentially moving the decimal of the number two places to the left. In undoing this you would have to move the decimal of the number two places to the right.
28.003 would then turn into 2,800.3
Unfortunately I cannot draw a chart on here but that is the best I can do.