The theatre had 2574 seats. There were 20% fewer $35-seats than $10-seats. 60% of the $10-seats and some $35-seats were sold. A total of $24015 was collected. How many seats were unsold?

	$35	$10	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 = 2574

1 u = 2574 ÷ 9 = 286

Total number of $10-seat tickets
= 5 u
= 5 x 286
= 1430

Number of $10-seat tickets sold
= 60% x 1430
= ⁶⁰₁₀₀ x 1430
= 858

Amount collected from $10-seat tickets sold
= 858 x 10
= $8580

Amount collected from $35-seat tickets sold
= 24015 - 8580
= $15435

Number of $35-seat tickets sold
= 15435 ÷ 35
= 441

Number of tickets sold
= 858 + 441
= 1299

Number of tickets left unsold
= 2574 - 1299
= 1275

Answer(s): 1275