Billy had twice as many beads as Paul. After Paul lost 20 beads and Billy bought 20 beads, Billy had 4 times as many beads as Paul. How many beads did Billy and Paul have altogether at first?
| |
Billy |
Paul |
Total |
| Before |
2x5 =
10 u |
1x5 =
5 u |
3x5 =
15 u |
| Change |
+ 20 |
- 20 |
|
| After |
4x3 =
12 u |
1x3 =
3 u |
5x3 =
15 u |
The number of beads that Paul lost and bought is the same. So, the total number of beads remains unchanged. Make the total number of beads the same. LCM of 3 and 5 is 15.
Number of beads that Billy bought
= 12 u - 10 u
= 2 u
2 u = 20
1 u = 20 ÷ 2 = 10
Number of cards that they had altogether at first
= 15 u
= 15 x 10
= 150
Answer(s): 150
