The theatre had 1904 seats. There were 25% fewer $35-seats than $10-seats. 50% of the $10-seats and some $35-seats were sold. A total of $18810 was collected. How many seats were unsold?

	$35	$10	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 = 1904

1 u = 1904 ÷ 7 = 272

Total number of $10-seat tickets
= 4 u
= 4 x 272
= 1088

Number of $10-seat tickets sold
= 50% x 1088
= ⁵⁰₁₀₀ x 1088
= 544

Amount collected from $10-seat tickets sold
= 544 x 10
= $5440

Amount collected from $35-seat tickets sold
= 18810 - 5440
= $13370

Number of $35-seat tickets sold
= 13370 ÷ 35
= 382

Number of tickets sold
= 544 + 382
= 926

Number of tickets left unsold
= 1904 - 926
= 978

Answer(s): 978