At a museum, each adult ticket cost $21 and each child ticket cost $10. On Thursday, the number of adult tickets sold was 80 less than the number of child tickets. On Friday, the number of adult tickets sold decreased by 50% while the number of child tickets sold increased by 15%. If a total of 917 tickets were sold on Friday, how much money was collected on Thursday?

	Adult tickets	Child tickets	Total tickets
Before	1 u	1 u + 80	2 u + 80
Change	- 0.5 u	+ 0.15 u + 12
After	0.5 u	1.15 u + 92	1.65 u + 92

50% x 1 u = ⁵⁰₁₀₀ x 1 u = 0.5 u 
15% x 1 u = ¹⁵₁₀₀ x 1 u = 0.15 u
15% x 80 = ¹⁵₁₀₀ x 80 = 12

Number of tickets sold on Friday
= 0.5 u + 1.15 u + 92
= 1.65 u + 92

1.65 u + 92 = 917
1.65 u = 917 - 92
1.65 u = 825

1 u = 825 ÷ 1.65 = 500

Amount collected from adult tickets on Thursday
= 1 u x 21
= 500 x 21
= $10500

Amount collected from child tickets on Thursday
= 10(1 u + 80)
= 10(500 + 80)
= 10 x 580
= $5800

Total amount collected on Thursday
= 10500 + 5800
= $16300

Answer(s):$16300