The auditorium had 2072 seats. There were 40% fewer $25-seats than $15-seats. 80% of the $15-seats and some $25-seats were sold. A total of $26040 was collected. How many seats were unsold?

	$25	$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 = 2072

1 u = 2072 ÷ 8 = 259

Total number of $15-seat tickets
= 5 u
= 5 x 259
= 1295

Number of $15-seat tickets sold
= 80% x 1295
= ⁸⁰₁₀₀ x 1295
= 1036

Amount collected from $15-seat tickets sold
= 1036 x 15
= $15540

Amount collected from $25-seat tickets sold
= 26040 - 15540
= $10500

Number of $25-seat tickets sold
= 10500 ÷ 25
= 420

Number of tickets sold
= 1036 + 420
= 1456

Number of tickets left unsold
= 2072 - 1456
= 616

Answer(s): 616