Question 974328
Right from the beginning, this can't be solved.
Attendance is 800, and even if all the tickets were for the balcony only, the receipts would be $4000.  I will edit to $7000 receipts, instead of $700.
.

concert=x
orchestra= 800-x

5x+10(800-x)=7000

5x+8000-10x=7000
-5x=-1000
x=200
800-x=600

Check
200*5=1000
600*10=6000

This works