Cindy and Gabby collected cards. Gabby gave 70% of her cards to Cindy. As a result, Cindy's cards increased by 10%. If Cindy had 693 cards left, find the total number of cards the two girls had at first.
| |
Comparing the change
in Gabby's cards |
Gabby |
Cindy |
| Before |
10x1 =
10 u |
|
10x7 =
70 u |
| Change |
- 7x1 =
- 7 u |
- 1x7 =
- 7 u |
+ 1x7 =
+ 7 u |
| After |
3x1 =
3 u |
|
11x7 =
77 u |
70% =
70100 =
710 10% =
10100 =
110 The number of cards that Cindy gave to Gabby is repeated. Make the number of cards that Cindy gave to Gabby the same. LCM of 1 and 7 is 7.
Number of cards that Cindy had in the end = 77 u
77 u = 693
1 u = 693 ÷ 77 = 9
Number of cards that Gabby and Cindy had at first
= 10 u + 70 u
= 80 u
= 80 x 9
= 720
Answer(s): 720
