At a museum, each adult ticket cost $31 and each child ticket cost $7. On Thursday, the number of adult tickets sold was 128 less than the number of child tickets. On Friday, the number of adult tickets sold decreased by 15% while the number of child tickets sold increased by 50%. If a total of 1837 tickets were sold on Friday, how much money was collected on Thursday?

	Adult tickets	Child tickets	Total tickets
Before	1 u	1 u + 128	2 u + 128
Change	- 0.15 u	+ 0.5 u + 64
After	0.85 u	1.5 u + 192	2.35 u + 192

15% x 1 u = ¹⁵₁₀₀ x 1 u = 0.15 u 
50% x 1 u = ⁵⁰₁₀₀ x 1 u = 0.5 u
50% x 128 = ⁵⁰₁₀₀ x 128 = 64

Number of tickets sold on Friday
= 0.85 u + 1.5 u + 192
= 2.35 u + 192

2.35 u + 192 = 1837
2.35 u = 1837 - 192
2.35 u = 1645

1 u = 1645 ÷ 2.35 = 700

Amount collected from adult tickets on Thursday
= 1 u x 31
= 700 x 31
= $21700

Amount collected from child tickets on Thursday
= 7(1 u + 128)
= 7(700 + 128)
= 7 x 828
= $5796

Total amount collected on Thursday
= 21700 + 5796
= $27496

Answer(s):$27496