I think there are 200 numbers as if we do 1000-800 (10-8 as there are only 2 numbers that can be divided by 5 exactly up to 10) that leaves 200 numbers
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 :)
The answer is the first one