Oliver had twice as many marbles as Oscar. After Oscar lost 16 marbles and Oliver bought 16 marbles, Oliver had 4 times as many marbles as Oscar. How many marbles did Oliver and Oscar have altogether at first?
| |
Oliver |
Oscar |
Total |
| Before |
2x5 =
10 u |
1x5 =
5 u |
3x5 =
15 u |
| Change |
+ 16 |
- 16 |
|
| After |
4x3 =
12 u |
1x3 =
3 u |
5x3 =
15 u |
The number of marbles that Oscar lost and bought is the same. So, the total number of marbles remains unchanged. Make the total number of marbles the same. LCM of 3 and 5 is 15.
Number of marbles that Oliver bought
= 12 u - 10 u
= 2 u
2 u = 16
1 u = 16 ÷ 2 = 8
Number of cards that they had altogether at first
= 15 u
= 15 x 8
= 120
Answer(s): 120
