The theatre had 1960 seats. There were 25% fewer $45-seats than $20-seats. 80% of the $20-seats and some $45-seats were sold. A total of $31465 was collected. How many seats were unsold?

	$45	$20	Total
Number	3 u	4 u	7 u

100% - 25% = 75%
⁷⁵₁₀₀ = ³₄

Total number of seats
= 3 u + 4 u
= 7 u

7 u = 1960

1 u = 1960 ÷ 7 = 280

Total number of $20-seat tickets
= 4 u
= 4 x 280
= 1120

Number of $20-seat tickets sold
= 80% x 1120
= ⁸⁰₁₀₀ x 1120
= 896

Amount collected from $20-seat tickets sold
= 896 x 20
= $17920

Amount collected from $45-seat tickets sold
= 31465 - 17920
= $13545

Number of $45-seat tickets sold
= 13545 ÷ 45
= 301

Number of tickets sold
= 896 + 301
= 1197

Number of tickets left unsold
= 1960 - 1197
= 763

Answer(s): 763