Betty spent
23 of her money on 12 files and 9 pens. The cost of each pen is 2 times the cost of each file. She bought some more files with
23 of her remaining money. How many files did Betty buy altogether?
| 12 files + 9 pens |
Remaining
amount |
Total
amount |
| 2 p = 30 u |
1 p = 15 u |
3 p |
12
files |
9
pens |
More files |
Left |
|
| |
|
2 |
1 |
|
| 12 u |
18 u |
10 u |
|
|
Cost of 1 file = 1 u
Cost of 1 pen = 2 u
Cost of 12 files = 12 x 1 u = 12 u
Cost of 9 pens = 9 x 2 u = 18 u
Cost of 12 files + 9 pens
= 12 u + 18 u
= 30 u
2 p = 30 u
1 p = 30 u ÷ 2 = 15 u
Amount of remaining money that Betty spent on buying more files
=
23 x 15 u
= 10 u
Number of files that Betty bought with
23 of her remaining money
= 10 u ÷ 1 u
= 10
Total number of files that Betty bought
= 12 + 10
= 22
Answer(s): 22
