At a stadium, each adult ticket cost $23 and each child ticket cost $7. On Monday, the number of adult tickets sold was 112 less than the number of child tickets. On Tuesday, the number of adult tickets sold decreased by 5% while the number of child tickets sold increased by 25%. If a total of 1680 tickets were sold on Tuesday, how much money was collected on Monday?

	Adult tickets	Child tickets	Total tickets
Before	1 u	1 u + 112	2 u + 112
Change	- 0.05 u	+ 0.25 u + 28
After	0.95 u	1.25 u + 140	2.2 u + 140

5% x 1 u = ⁵₁₀₀ x 1 u = 0.05 u 
25% x 1 u = ²⁵₁₀₀ x 1 u = 0.25 u
25% x 112 = ²⁵₁₀₀ x 112 = 28

Number of tickets sold on Tuesday
= 0.95 u + 1.25 u + 140
= 2.2 u + 140

2.2 u + 140 = 1680
2.2 u = 1680 - 140
2.2 u = 1540

1 u = 1540 ÷ 2.2 = 700

Amount collected from adult tickets on Monday
= 1 u x 23
= 700 x 23
= $16100

Amount collected from child tickets on Monday
= 7(1 u + 112)
= 7(700 + 112)
= 7 x 812
= $5684

Total amount collected on Monday
= 16100 + 5684
= $21784

Answer(s):$21784