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 30 percent, what is the discount rate on mysteries?  Choose the correct choice from the following choices: A) 17.18% B) 12% C) 13% D) 14% E) 15%
Let B be the discount on biographies and M be the discount on mysteries   So., B + M = 0.30 -----(1)   17.18%nd   (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 = 0.1718 = 17.18   17.18%
<result>A</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 30 percent, what is the discount rate on mysteries?