Fanny and Eva have some stamps. If Fanny gives 10 stamps to Eva, Eva will have 5 times the number of stamps as Fanny. If Eva gives 40 stamps to Fanny, Fanny will have
25 as many stamps as Eva. How many stamps does Fanny have at first?
| |
Case 1 |
Case 2 |
| |
Fanny |
Eva |
Fanny |
Eva |
| Before |
7 u + 10 |
35 u - 10 |
12 u - 40 |
30 u + 40 |
| Change |
- 10 |
+ 10 |
+ 40 |
- 40 |
| After |
1x7 =
7 u |
5x7 =
35 u |
2x6 =
12 u |
5x6 =
30 u |
The total number of stamps in both cases remains unchanged. Make the total number of stamps in both cases the same. LCM of 6 and 7 is 42.
Number of stamps that Fanny had at first is the same in both cases.
12 u - 40 = 7 u + 10
12 u - 7 u = 10 + 40
5 u = 50
1 u = 10
Number of stamps that Fanny had at first
= 7 u + 10
= 7 x 10 + 10
= 70 + 10
= 80
Answer(s): 80
