At a zoo, each adult ticket cost $31 and each child ticket cost $11. On Tuesday, the number of adult tickets sold was 120 less than the number of child tickets. On Wednesday, the number of adult tickets sold decreased by 15% while the number of child tickets sold increased by 10%. If a total of 522 tickets were sold on Wednesday, how much money was collected on Tuesday?

	Adult tickets	Child tickets	Total tickets
Before	1 u	1 u + 120	2 u + 120
Change	- 0.15 u	+ 0.1 u + 12
After	0.85 u	1.1 u + 132	1.95 u + 132

15% x 1 u = ¹⁵₁₀₀ x 1 u = 0.15 u 
10% x 1 u = ¹⁰₁₀₀ x 1 u = 0.1 u
10% x 120 = ¹⁰₁₀₀ x 120 = 12

Number of tickets sold on Wednesday
= 0.85 u + 1.1 u + 132
= 1.95 u + 132

1.95 u + 132 = 522
1.95 u = 522 - 132
1.95 u = 390

1 u = 390 ÷ 1.95 = 200

Amount collected from adult tickets on Tuesday
= 1 u x 31
= 200 x 31
= $6200

Amount collected from child tickets on Tuesday
= 11(1 u + 120)
= 11(200 + 120)
= 11 x 320
= $3520

Total amount collected on Tuesday
= 6200 + 3520
= $9720

Answer(s):$9720