Risa spent
34 of her money on 10 pens and 5 notebooks. The cost of each notebook is 4 times the cost of each pen. She bought some more pens with
45 of her remaining money. How many pens did Risa buy altogether?
| 10 pens + 5 notebooks |
Remaining
amount |
Total
amount |
| 3 p = 30 u |
1 p = 10 u |
4 p |
10
pens |
5
notebooks |
More pens |
Left |
|
| |
|
4 |
1 |
|
| 10 u |
20 u |
8 u |
|
|
Cost of 1 pen = 1 u
Cost of 1 notebook = 4 u
Cost of 10 pens = 10 x 1 u = 10 u
Cost of 5 notebooks = 5 x 4 u = 20 u
Cost of 10 pens + 5 notebooks
= 10 u + 20 u
= 30 u
3 p = 30 u
1 p = 30 u ÷ 3 = 10 u
Amount of remaining money that Risa spent on buying more pens
=
45 x 10 u
= 8 u
Number of pens that Risa bought with
45 of her remaining money
= 8 u ÷ 1 u
= 8
Total number of pens that Risa bought
= 10 + 8
= 18
Answer(s): 18
