Cathy and Xylia collected coins. Xylia gave 70% of her coins to Cathy. As a result, Cathy's coins increased by 40%. If Cathy had 539 coins left, find the total number of coins the two girls had at first.
| |
Comparing the change
in Xylia's coins |
Xylia |
Cathy |
| Before |
10x2 =
20 u |
|
5x7 =
35 u |
| Change |
- 7x2 =
- 14 u |
- 2x7 =
- 14 u |
+ 2x7 =
+ 14 u |
| After |
3x2 =
6 u |
|
7x7 =
49 u |
70% =
70100 =
710 40% =
40100 =
25 The number of coins that Cathy gave to Xylia is repeated. Make the number of coins that Cathy gave to Xylia the same. LCM of 2 and 7 is 14.
Number of coins that Cathy had in the end = 49 u
49 u = 539
1 u = 539 ÷ 49 = 11
Number of coins that Xylia and Cathy had at first
= 20 u + 35 u
= 55 u
= 55 x 11
= 605
Answer(s): 605
