Luis is selling 500 non-fiction books. He sold 75% of them at $8 each, 60% of the remainder at a discount of 25% and the rest at cost price. He made a profit of $2477. Find the cost price of a non-fiction book.

Price	$8	$6	Cost Price
Percent	75%	25%
		15%	10%
Number	375	75	Not needed
Amount collected	$3000	$450	Not needed

Number of non-fiction books sold at $8
= 75% x 500
= ⁷⁵₁₀₀ x 500
= 375

Price after 25% discount
= 75% x 8
= ⁷⁵₁₀₀ x 8
= $6

Remaining non-fiction books
= 500 - 375
= 125

Number of non-fiction books sold at $6
= 60% x 125
= ⁶⁰₁₀₀ x 125
= 75

Number of non-fiction books sold at $8 or 25% discount
= 375 + 75
= 450

Total amount collected from the sale of 375 non-fiction books
= 375 x 8
= $3000

Total amount collected from the sale of the other 75 non-fiction books
= 75 x 6
= $450

Total amount collected from the sale of non-fiction books sold at $8 or 25% discount
= 3000 + 450
= $3450

Cost price of 450 non-fiction books
= 3450 - 2477
= $1350

Cost price of 1 non-fiction book
= 1350 ÷ 450
= $3

Answer(s): $3