Answer:
12 10 dollar bills.
Explanation:
you need 12 10 dollar bills bc i added 3 50 dollar bills (150), 18 20 dollar bills (360), which was 510. after i got 510, i figured out how much was needed left, so i subtracted 630 minus 510 which was 120. in the end i knew 10x12 was 120 so you need twelve 10 dollar bills.