In a tin can, the ratio of the number of red beads to the number of blue beads was 1 : 3. Each time, 3 red and 7 blue beads were taken out of the tin can. A while later, only 164 blue beads were left in the tin can. What was the total number of beads in the tin can at first?
| |
Red beads |
Blue beads |
| Before |
1x3 =
3 u |
3x3 =
9 u |
| Change |
- 3 u |
- 7 u |
| After |
0 |
164 |
Since there is no red beads left, this means that the number of red marbles at first is the same as the number of red marbles taken out.
Make the number of red beads at first and taken out the same. LCM of 1 and 3 is 3.
Number of blue beads in the end
= 9 u - 7 u
= 2 u
2 u = 164
1 u = 164 ÷ 2 = 82
Total number of beads in the tin can at first
= 3 u + 9 u
= 12 u
= 12 x 82
= 984
Answer: 984
