The auditorium had 2493 seats. There were 20% fewer $40-seats than $5-seats. 60% of the $5-seats and some $40-seats were sold. A total of $18435 was collected. How many seats were unsold?

	$40	$5	Total
Number	4 u	5 u	9 u

100% - 20% = 80%
⁸⁰₁₀₀ = ⁴₅

Total number of seats
= 4 u + 5 u
= 9 u

9 u = 2493

1 u = 2493 ÷ 9 = 277

Total number of $5-seat tickets
= 5 u
= 5 x 277
= 1385

Number of $5-seat tickets sold
= 60% x 1385
= ⁶⁰₁₀₀ x 1385
= 831

Amount collected from $5-seat tickets sold
= 831 x 5
= $4155

Amount collected from $40-seat tickets sold
= 18435 - 4155
= $14280

Number of $40-seat tickets sold
= 14280 ÷ 40
= 357

Number of tickets sold
= 831 + 357
= 1188

Number of tickets left unsold
= 2493 - 1188
= 1305

Answer(s): 1305