A bookstore ordered 10 boxes of hardcover books and some boxes of paperback books. Hardcovers cost twice as much per box as paperbacks. Due to an order error, the quantities were swapped, increasing the bill by 20%. What is the ratio of hardcover to paperback boxes originally?

उत्तर देखें और व्याख्या

उत्तर: (A) 4:7

व्याख्या

2x + 10 = 1.2(20 + x) gives x = 17.5, so 10 : 17.5 = 4 : 7.