Dana and Betty collected pens. Betty gave 80% of her pens to Dana. As a result, Dana's pens increased by 25%. If Dana had 80 pens left, find the total number of pens the two girls had at first.
| |
Comparing the change
in Betty's pens |
Betty |
Dana |
| Before |
5x1 =
5 u |
|
4x4 =
16 u |
| Change |
- 4x1 =
- 4 u |
- 1x4 =
- 4 u |
+ 1x4 =
+ 4 u |
| After |
1x1 =
1 u |
|
5x4 =
20 u |
80% =
80100 =
45 25% =
25100 =
14 The number of pens that Dana gave to Betty is repeated. Make the number of pens that Dana gave to Betty the same. LCM of 1 and 4 is 4.
Number of pens that Dana had in the end = 20 u
20 u = 80
1 u = 80 ÷ 20 = 4
Number of pens that Betty and Dana had at first
= 5 u + 16 u
= 21 u
= 21 x 4
= 84
Answer(s): 84
