In a pouch, the ratio of the number of black beads to the number of brown beads was 1 : 3. Each time, 5 black and 6 brown beads were taken out of the pouch. A while later, only 135 brown beads were left in the pouch. What was the total number of beads in the pouch at first?
| |
Black beads |
Brown beads |
| Before |
1x5 =
5 u |
3x5 =
15 u |
| Change |
- 5 u |
- 6 u |
| After |
0 |
135 |
Since there is no black beads left, this means that the number of black marbles at first is the same as the number of black marbles taken out.
Make the number of black beads at first and taken out the same. LCM of 1 and 5 is 5.
Number of brown beads in the end
= 15 u - 6 u
= 9 u
9 u = 135
1 u = 135 ÷ 9 = 15
Total number of beads in the pouch at first
= 5 u + 15 u
= 20 u
= 20 x 15
= 300
Answer: 300
