In a pouch, the ratio of the number of brown marbles to the number of blue marbles was 1 : 4. Each time, 4 brown and 6 blue marbles were taken out of the pouch. A while later, only 80 blue marbles were left in the pouch. What was the total number of marbles in the pouch at first?
| |
Brown marbles |
Blue marbles |
| Before |
1x4 =
4 u |
4x4 =
16 u |
| Change |
- 4 u |
- 6 u |
| After |
0 |
80 |
Since there is no brown marbles left, this means that the number of brown marbles at first is the same as the number of brown marbles taken out.
Make the number of brown marbles at first and taken out the same. LCM of 1 and 4 is 4.
Number of blue marbles in the end
= 16 u - 6 u
= 10 u
10 u = 80
1 u = 80 ÷ 10 = 8
Total number of marbles in the pouch at first
= 4 u + 16 u
= 20 u
= 20 x 8
= 160
Answer: 160
