Min spent
27 of her money on 10 rulers and 7 pens. The cost of one pen was twice the cost of one ruler. She bought some more pens with
13 of her remaining money. How many pens did Min buy altogether?
10 rulers and
7 pens |
Remaining amount |
| 2x3 |
5x3 |
| |
More pens |
Left |
| |
1x5 |
2x5 |
| 6 p |
5 p |
10 p |
Cost of 1 ruler = 1 u
Cost of 1 pen = 2 u
Cost of 10 rulers = 10 x 1 u = 10 u
Cost of 7 pens = 7 x 2 u = 14 u
Total cost of 10 rulers and 7 pens
= 10 u + 14 u
= 24 u
6 p = 24 u
1 p = 24 ÷ 6 = 4 u
Amount that Min used to buy more pens
= 5 p
= 5 x 4 u
= 20 u
Number of more pens that Min bought
= 20 u ÷ 2 u
= 10
Total number of pens that Min bought
= 7 + 10
= 17
Answer(s): 17
