The auditorium had 1080 seats. There were 40% fewer $45-seats than $20-seats. 60% of the $20-seats and some $45-seats were sold. A total of $23940 was collected. How many seats were unsold?

	$45	$20	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 = 1080

1 u = 1080 ÷ 8 = 135

Total number of $20-seat tickets
= 5 u
= 5 x 135
= 675

Number of $20-seat tickets sold
= 60% x 675
= ⁶⁰₁₀₀ x 675
= 405

Amount collected from $20-seat tickets sold
= 405 x 20
= $8100

Amount collected from $45-seat tickets sold
= 23940 - 8100
= $15840

Number of $45-seat tickets sold
= 15840 ÷ 45
= 352

Number of tickets sold
= 405 + 352
= 757

Number of tickets left unsold
= 1080 - 757
= 323

Answer(s): 323