Last Monday, Pierre had twice as many buttons as Mark. Today, Pierre gives 9 of his buttons to his brother. Now, Mark has twice as many buttons as Pierre. How many buttons does Mark have?
| |
Pierre |
Mark |
| Before |
2x2 =
4 u |
1x2 =
2 u |
| Change |
- 9 |
|
| After |
1 u |
2 u |
The number of buttons that Mark had at first and in the end remains unchanged. Make the number of buttons that Mark has the same. LCM of 1 and 2 is 2.
Number of buttons that Pierre gives to his brother
= 4 u - 1 u
= 3 u
3 u = 9
1 u = 9 ÷ 3 = 3
Number of buttons that Mark has
= 2 u
= 2 x 3
= 6
Answer(s): 6
