A person purchases 90 shirts and sells 40 shirts at a gain of 10% and 50 shirts at a gain of 20%. If he sold all of them at a uniform profit of 15%, then he would have got $40 less. The cost price of each shirt is:	Choices.
A) 10  B) 30  C) 80  D) 40  E) 90
C   80   Let C.P. of shirt be $x.   Then, C.P. of 90 shirts = $90x.   [(110% of 40x) + (120% of 50x)] - (115% of 90x) = 40   44x + 60x - 103.5x = 40   0.5x = 40 =&gt; x = 80
<result>C</result>
A person purchases 90 shirts and sells 40 shirts at a gain of 10% and 50 shirts at a gain of 20%. If he sold all of them at a uniform profit of 15%, then he would have got $40 less. The cost price of each shirt is: