The theatre had 1728 seats. There were 40% fewer $25-seats than $20-seats. 80% of the $20-seats and some $25-seats were sold. A total of $26905 was collected. How many seats were unsold?

	$25	$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 = 1728

1 u = 1728 ÷ 8 = 216

Total number of $20-seat tickets
= 5 u
= 5 x 216
= 1080

Number of $20-seat tickets sold
= 80% x 1080
= ⁸⁰₁₀₀ x 1080
= 864

Amount collected from $20-seat tickets sold
= 864 x 20
= $17280

Amount collected from $25-seat tickets sold
= 26905 - 17280
= $9625

Number of $25-seat tickets sold
= 9625 ÷ 25
= 385

Number of tickets sold
= 864 + 385
= 1249

Number of tickets left unsold
= 1728 - 1249
= 479

Answer(s): 479