A bookstore has a shelf that contains biographies which normally sell for $20 each and mysteries that normally sell for $12 each. During a sale, the biographies and mysteries are discounted at different rates so that a customer saves a total of $19 from the normal price by buying 5 discounted biographies and 3 discounted mysteries. If the sum of the discount rates for the two types of books is 43 percent, what is the discount rate on mysteries?
Answers:
A) 24%	B) 25%	C) 30%	D) 37.5%	E) 40%
Let B be the discount on biographies and M be the discount on mysteries   So., B + M = 0.435 -----(1)   And   (20*5 + 12*3) - (20*5*(1-B) + 12*3*(1-M)) = 19   --&gt; 100(1-(1-B)) + 36(1-(1-M) = 19   100B + 36M = 19 ------(2)   Solving 12., we get M = 0.375 = 37.5%   37.5%
<result>D</result>
A bookstore has a shelf that contains biographies which normally sell for $20 each and mysteries that normally sell for $12 each. During a sale, the biographies and mysteries are discounted at different rates so that a customer saves a total of $19 from the normal price by buying 5 discounted biographies and 3 discounted mysteries. If the sum of the discount rates for the two types of books is 43 percent, what is the discount rate on mysteries?