Abi and Gabby collected pens. Gabby gave 80% of her pens to Abi. As a result, Abi's pens increased by 30%. If Abi had 624 pens left, find the total number of pens the two girls had at first.
| |
Comparing the change
in Gabby's pens |
Gabby |
Abi |
| Before |
5x3 =
15 u |
|
10x4 =
40 u |
| Change |
- 4x3 =
- 12 u |
- 3x4 =
- 12 u |
+ 3x4 =
+ 12 u |
| After |
1x3 =
3 u |
|
13x4 =
52 u |
80% =
80100 =
45 30% =
30100 =
310 The number of pens that Abi gave to Gabby is repeated. Make the number of pens that Abi gave to Gabby the same. LCM of 3 and 4 is 12.
Number of pens that Abi had in the end = 52 u
52 u = 624
1 u = 624 ÷ 52 = 12
Number of pens that Gabby and Abi had at first
= 15 u + 40 u
= 55 u
= 55 x 12
= 660
Answer(s): 660
