At a bird park, each adult ticket cost $21 and each child ticket cost $15. On Thursday, the number of adult tickets sold was 148 less than the number of child tickets. On Friday, the number of adult tickets sold decreased by 40% while the number of child tickets sold increased by 50%. If a total of 1692 tickets were sold on Friday, how much money was collected on Thursday?

	Adult tickets	Child tickets	Total tickets
Before	1 u	1 u + 148	2 u + 148
Change	- 0.4 u	+ 0.5 u + 74
After	0.6 u	1.5 u + 222	2.1 u + 222

40% x 1 u = ⁴⁰₁₀₀ x 1 u = 0.4 u 
50% x 1 u = ⁵⁰₁₀₀ x 1 u = 0.5 u
50% x 148 = ⁵⁰₁₀₀ x 148 = 74

Number of tickets sold on Friday
= 0.6 u + 1.5 u + 222
= 2.1 u + 222

2.1 u + 222 = 1692
2.1 u = 1692 - 222
2.1 u = 1470

1 u = 1470 ÷ 2.1 = 700

Amount collected from adult tickets on Thursday
= 1 u x 21
= 700 x 21
= $14700

Amount collected from child tickets on Thursday
= 15(1 u + 148)
= 15(700 + 148)
= 15 x 848
= $12720

Total amount collected on Thursday
= 14700 + 12720
= $27420

Answer(s):$27420