Diana had thrice as many pens as files. After giving away 22 pens and selling 21 pens, she found out that she had twice as many pens as files left.
- How many pens did Diana have at first?
- How many pens and files did Diana have altogether at first?
|
Pens |
Files |
Total |
Before |
3 u |
1 u |
4 u |
Change 1 |
- 22 |
|
- 1 u |
Change 2 |
- 21 |
|
After |
2 u |
1 u |
3 u |
(a)
The number of files remains unchanged.
Number of pens that Diana gave away or sold
= 3 u - 2 u
= 1 u
1 u = 22 + 21 = 43
Number of pens that Diana had at first
= 3 u
= 3 x 43
= 129
(b)
Total number of pens and files that Diana had at first
= 1 u + 3 u
= 4 u
= 4 x 43
= 172
Answer(s): (a) 129; (b) 172