The theatre had 1512 seats. There were 40% fewer $30-seats than $20-seats. 80% of the $20-seats and some $30-seats were sold. A total of $26430 was collected. How many seats were unsold?

	$30	$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 = 1512

1 u = 1512 ÷ 8 = 189

Total number of $20-seat tickets
= 5 u
= 5 x 189
= 945

Number of $20-seat tickets sold
= 80% x 945
= ⁸⁰₁₀₀ x 945
= 756

Amount collected from $20-seat tickets sold
= 756 x 20
= $15120

Amount collected from $30-seat tickets sold
= 26430 - 15120
= $11310

Number of $30-seat tickets sold
= 11310 ÷ 30
= 377

Number of tickets sold
= 756 + 377
= 1133

Number of tickets left unsold
= 1512 - 1133
= 379

Answer(s): 379