Charlie had some stamps at first. After he bought another 42 stamps, he had thrice as many stamps as before. How many stamps did Charlie have at first?
| |
Stamps |
| Before |
1 u |
| Change |
+ 42 |
| After |
1 u + 42 = 3 u |
Number of stamps after he bought = 1 u + 42
Number of stamps that is thrice as many stamps as before = 3 x 1 u = 3 u
3 u = 1 u + 42
3 u - 1 u = 42
2 u = 42
1 u = 42 ÷ 2 = 21
Number of stickers that Kim had at first
= 1 u
= 21
Answer(s): 21
