The opera house had 1120 seats. There were 40% fewer $30-seats than $20-seats. 80% of the $20-seats and some $30-seats were sold. A total of $20230 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 = 1120

1 u = 1120 ÷ 8 = 140

Total number of $20-seat tickets
= 5 u
= 5 x 140
= 700

Number of $20-seat tickets sold
= 80% x 700
= ⁸⁰₁₀₀ x 700
= 560

Amount collected from $20-seat tickets sold
= 560 x 20
= $11200

Amount collected from $30-seat tickets sold
= 20230 - 11200
= $9030

Number of $30-seat tickets sold
= 9030 ÷ 30
= 301

Number of tickets sold
= 560 + 301
= 861

Number of tickets left unsold
= 1120 - 861
= 259

Answer(s): 259