Justin is selling 900 magazines. 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 $2143. Find the cost price of a magazine.

Price	$8	$6	Cost Price
Percent	75%	25%
		15%	10%
Number	675	135	Not needed
Amount collected	$5400	$810	Not needed

Number of magazines sold at $8
= 75% x 900
= ⁷⁵₁₀₀ x 900
= 675

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

Remaining magazines
= 900 - 675
= 225

Number of magazines sold at $6
= 60% x 225
= ⁶⁰₁₀₀ x 225
= 135

Number of magazines sold at $8 or 25% discount
= 675 + 135
= 810

Total amount collected from the sale of 675 magazines
= 675 x 8
= $5400

Total amount collected from the sale of the other 135 magazines
= 135 x 6
= $810

Total amount collected from the sale of magazines sold at $8 or 25% discount
= 5400 + 810
= $6210

Cost price of 810 magazines
= 6210 - 2143
= $8910

Cost price of 1 magazine
= 8910 ÷ 810
= $11

Answer(s): $11