Rachel and Yen had an equal number of stamps at first. Rachel used
13 of her stamps and Yen used
17 of her stamps. They used 20 stamps altogether. How many stamps did Yen have in the end?
|
Rachel |
Yen |
Before |
3x7 = 21 u |
7x3 = 21 u |
Change |
- 1x7 = - 7 u |
- 1x3 = - 3 u |
After |
2x7 = 14 u |
6x3 = 18 u |
The number of stamps that Rachel and Yen each had at first is the same. Make the number of stamps that Rachel and Yen each had at first the same. LCM of 3 and 7 is 21.
Number of stamps that Rachel and Yen used
= 7 u + 3 u
= 10 u
10 u = 20
1 u = 20 ÷ 10 = 2
Number of stamps that Yen had in the end
= 18 u
= 18 x 2
= 36
Answer(s): 36