Albert had 4 times as many buttons as Luis at first. Then each of them bought an equal number of new buttons. In the end, Luis had 21 buttons and Albert had 3 times as many buttons as Luis. How many buttons did both of them buy altogether?
| |
Albert |
Luis |
Difference |
| Before |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
| Change |
+ ? |
+ ? |
|
| After |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
The difference in the number of buttons at first and in the end remains unchanged. Make the difference in the number of buttons at first and in the end the same. LCM of 3 and 2 is 6.
Number of buttons that Luis had in the end = 3 u
3 u = 21
1 u = 21 ÷ 3 = 7
Number of buttons that Albert bought
= 9 u - 8 u
= 1 u
Number of buttons that both of them bought altogether
= 2 x 1 u
= 2 u
= 2 x 7
= 14
Answer(s): 14
