The drama centre had 872 seats. There were 40% fewer $50-seats than $15-seats. 60% of the $15-seats and some $50-seats were sold. A total of $20005 was collected. How many seats were unsold?

	$50	$15	Total
Number	3 u	5 u	8 u

100% - 40% = 60%
⁶⁰₁₀₀ = ³₅

Total number of seats
= 3 u + 5 u
= 8 u

8 u = 872

1 u = 872 ÷ 8 = 109

Total number of $15-seat tickets
= 5 u
= 5 x 109
= 545

Number of $15-seat tickets sold
= 60% x 545
= ⁶⁰₁₀₀ x 545
= 327

Amount collected from $15-seat tickets sold
= 327 x 15
= $4905

Amount collected from $50-seat tickets sold
= 20005 - 4905
= $15100

Number of $50-seat tickets sold
= 15100 ÷ 50
= 302

Number of tickets sold
= 327 + 302
= 629

Number of tickets left unsold
= 872 - 629
= 243

Answer(s): 243