Shiyun spent
23 of her money on 15 pens and 9 notebooks. The cost of each notebook is 3 times the cost of each pen. She bought some more pens with
23 of her remaining money. How many pens did Shiyun buy altogether?
| 15 pens + 9 notebooks |
Remaining
amount |
Total
amount |
| 2 p = 42 u |
1 p = 21 u |
3 p |
15
pens |
9
notebooks |
More pens |
Left |
|
| |
|
2 |
1 |
|
| 15 u |
27 u |
14 u |
|
|
Cost of 1 pen = 1 u
Cost of 1 notebook = 3 u
Cost of 15 pens = 15 x 1 u = 15 u
Cost of 9 notebooks = 9 x 3 u = 27 u
Cost of 15 pens + 9 notebooks
= 15 u + 27 u
= 42 u
2 p = 42 u
1 p = 42 u ÷ 2 = 21 u
Amount of remaining money that Shiyun spent on buying more pens
=
23 x 21 u
= 14 u
Number of pens that Shiyun bought with
23 of her remaining money
= 14 u ÷ 1 u
= 14
Total number of pens that Shiyun bought
= 15 + 14
= 29
Answer(s): 29
