The opera house had 1659 seats. There were 25% fewer $45-seats than $15-seats. 50% of the $15-seats and some $45-seats were sold. A total of $27360 was collected. How many seats were unsold?

	$45	$15	Total
Number	3 u	4 u	7 u

100% - 25% = 75%
⁷⁵₁₀₀ = ³₄

Total number of seats
= 3 u + 4 u
= 7 u

7 u = 1659

1 u = 1659 ÷ 7 = 237

Total number of $15-seat tickets
= 4 u
= 4 x 237
= 948

Number of $15-seat tickets sold
= 50% x 948
= ⁵⁰₁₀₀ x 948
= 474

Amount collected from $15-seat tickets sold
= 474 x 15
= $7110

Amount collected from $45-seat tickets sold
= 27360 - 7110
= $20250

Number of $45-seat tickets sold
= 20250 ÷ 45
= 450

Number of tickets sold
= 474 + 450
= 924

Number of tickets left unsold
= 1659 - 924
= 735

Answer(s): 735