Mary and Shiyun have some cards. If Mary gives 35 cards to Shiyun, Shiyun will have 4 times the number of cards as Mary. If Shiyun gives 4 cards to Mary, Mary will have
25 as many cards as Shiyun. How many cards does Mary have at first?
|
Case 1 |
Case 2 |
|
Mary |
Shiyun |
Mary |
Shiyun |
Before |
7 u + 35 |
28 u - 35 |
10 u - 4 |
25 u + 4 |
Change |
- 35 |
+ 35 |
+ 4 |
- 4 |
After |
1x7 = 7 u |
4x7 = 28 u |
2x5 = 10 u |
5x5 = 25 u |
The total number of cards in both cases remains unchanged. Make the total number of cards in both cases the same. LCM of 5 and 7 is 35.
Number of cards that Mary had at first is the same in both cases.
10 u - 4 = 7 u + 35
10 u - 7 u = 35 + 4
3 u = 39
1 u = 13
Number of cards that Mary had at first
= 7 u + 35
= 7 x 13 + 35
= 91 + 35
= 126
Answer(s): 126