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 27 percent, what is the discount rate on mysteries?	Choose one
A) 10%
B) 11%
C) 12.5%
D) 13%
E) 14%
Let B be the discount on biographies and M be the discount on mysteries   So., B + M = 0.27 -----(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 = 0.125 = 12.5%   12.5%
<result>C</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 27 percent, what is the discount rate on mysteries?