Oliver had 6 times as many cards as Oscar at first. Then each of them bought an equal number of new cards. In the end, Oscar had 35 cards and Oliver had 5 times as many cards as Oscar. How many cards did both of them buy altogether?
| |
Oliver |
Oscar |
Difference |
| Before |
6x4 =
24 u |
1x4 =
4 u |
5x4 =
20 u |
| Change |
+ ? |
+ ? |
|
| After |
5x5 =
25 u |
1x5 =
5 u |
4x5 =
20 u |
The difference in the number of cards at first and in the end remains unchanged. Make the difference in the number of cards at first and in the end the same. LCM of 5 and 4 is 20.
Number of cards that Oscar had in the end = 5 u
5 u = 35
1 u = 35 ÷ 5 = 7
Number of cards that Oliver bought
= 25 u - 24 u
= 1 u
Number of cards that both of them bought altogether
= 2 x 1 u
= 2 u
= 2 x 7
= 14
Answer(s): 14
