The manager made a good estimate-
200 child tickets x 6 = 1200
37 rows x 23 seats per row = 851 total seats
851 total seats - 200 child tickets sold (given) = 651 seats
651 seats left x 8 dollars per adult = 5208
so the amount raised was 1200 + 5208 = 6408 not far from the managers estimate!