Shiyun had 72 more pens than Tiffany. After Tiffany gave away
25 of her pens, Shiyun had thrice as many pens as Tiffany. How many pens did Tiffany have at first?
| |
Shiyun |
Tiffany |
Comparing Shiyun
and Tiffany at first |
72 more |
|
| Before |
9 u |
5 u |
| Change |
|
- 2 u |
| After |
|
3 u |
Comparing Shiyun
and Tiffany in the end |
3x3 =
9 u |
1x3 =
3 u |
The number of pens that Shiyun had at first and in the end remains unchanged. Make the number of pens that Shiyun had the same. LCM of 9 and 3 is 9.
Number of pens that Shiyun had more than Tiffany at first
= 9 u - 5 u
= 4 u
4 u = 72
1 u = 72 ÷ 4 = 18
Number of pens that Tiffany had at first
= 5 u
= 5 x 18
= 90
Answer(s): 90
