Irene spent
34 of her money on 15 pencils and 7 files. The cost of each file is 3 times the cost of each pencil. She bought some more pencils with
56 of her remaining money. How many pencils did Irene buy altogether?
| 15 pencils + 7 files |
Remaining
amount |
Total
amount |
| 3 p = 36 u |
1 p = 12 u |
4 p |
15
pencils |
7
files |
More pencils |
Left |
|
| |
|
5 |
1 |
|
| 15 u |
21 u |
10 u |
|
|
Cost of 1 pencil = 1 u
Cost of 1 file = 3 u
Cost of 15 pencils = 15 x 1 u = 15 u
Cost of 7 files = 7 x 3 u = 21 u
Cost of 15 pencils + 7 files
= 15 u + 21 u
= 36 u
3 p = 36 u
1 p = 36 u ÷ 3 = 12 u
Amount of remaining money that Irene spent on buying more pencils
=
56 x 12 u
= 10 u
Number of pencils that Irene bought with
56 of her remaining money
= 10 u ÷ 1 u
= 10
Total number of pencils that Irene bought
= 15 + 10
= 25
Answer(s): 25
