In a bag, the ratio of the number of white marbles to the number of red marbles was 1 : 3. Each time, 4 white and 6 red marbles were taken out of the bag. A while later, only 48 red marbles were left in the bag. What was the total number of marbles in the bag at first?
| |
White marbles |
Red marbles |
| Before |
1x4 =
4 u |
3x4 =
12 u |
| Change |
- 4 u |
- 6 u |
| After |
0 |
48 |
Since there is no white marbles left, this means that the number of white marbles at first is the same as the number of white marbles taken out.
Make the number of white marbles at first and taken out the same. LCM of 1 and 4 is 4.
Number of red marbles in the end
= 12 u - 6 u
= 6 u
6 u = 48
1 u = 48 ÷ 6 = 8
Total number of marbles in the bag at first
= 4 u + 12 u
= 16 u
= 16 x 8
= 128
Answer: 128
