The cost of a tray was 3 times the cost of a cup. Patricia used 7/9 of her
money to buy 5 trays and 20 cups. She then used 9/10 of her remaining
money to buy some more trays. How many more trays did she buy?
5 trays + 20 cups = (5 + 20/3) trays
= 35/3 trays
35/3 trays ---> 7/9 of her money
1 tray ---> 1/15 of her money
9/10 of her remaining money (2/9) = 9/10 * 2/9
= 1/5 of her money
1/5 / 1/15 = 3
She bought 3 more trays with her remaining money.
Where X = cups and B = trays, it follows that: B=3X Since D is Patricia's total amount of money, it follows that: 7/9D= 5B + 20X = 15X + 20X = 35X D-7/9D = 2/9D (cash rest) 2/9 × 9/10 = 1/5 (9/10 of the restate money, used to buy more trays) If, with 7/9 the money, she bought 35 cups, with 1/5 the money, she will buy: 7/9 -- 35 X = 7×7/9 1/5--- - X
X = 49/9 cups As each tray is equivalent to 3 cups, she will buy with this amount: 1/3 × 49/9 = 49/27 trays As a tray cannot be a quantity with decimal places, it is assumed that she will be able to buy only one tray.
