The drama centre had 2025 seats. There were 20% fewer $45-seats than $10-seats. 80% of the $10-seats and some $45-seats were sold. A total of $25650 was collected. How many seats were unsold?

	$45	$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 = 2025

1 u = 2025 ÷ 9 = 225

Total number of $10-seat tickets
= 5 u
= 5 x 225
= 1125

Number of $10-seat tickets sold
= 80% x 1125
= ⁸⁰₁₀₀ x 1125
= 900

Amount collected from $10-seat tickets sold
= 900 x 10
= $9000

Amount collected from $45-seat tickets sold
= 25650 - 9000
= $16650

Number of $45-seat tickets sold
= 16650 ÷ 45
= 370

Number of tickets sold
= 900 + 370
= 1270

Number of tickets left unsold
= 2025 - 1270
= 755

Answer(s): 755