Yoko and Eva have some stamps. If Yoko gives 12 stamps to Eva, Eva will have 4 times the number of stamps as Yoko. If Eva gives 15 stamps to Yoko, Yoko will have
25 as many stamps as Eva. How many stamps does Yoko have at first?
|
Case 1 |
Case 2 |
|
Yoko |
Eva |
Yoko |
Eva |
Before |
7 u + 12 |
28 u - 12 |
10 u - 15 |
25 u + 15 |
Change |
- 12 |
+ 12 |
+ 15 |
- 15 |
After |
1x7 = 7 u |
4x7 = 28 u |
2x5 = 10 u |
5x5 = 25 u |
The total number of stamps in both cases remains unchanged. Make the total number of stamps in both cases the same. LCM of 5 and 7 is 35.
Number of stamps that Yoko had at first is the same in both cases.
10 u - 15 = 7 u + 12
10 u - 7 u = 12 + 15
3 u = 27
1 u = 9
Number of stamps that Yoko had at first
= 7 u + 12
= 7 x 9 + 12
= 63 + 12
= 75
Answer(s): 75