In a tin can, the ratio of the number of red beads to the number of silver beads was 1 : 4. Each time, 5 red and 7 silver beads were taken out of the tin can. A while later, only 52 silver beads were left in the tin can. What was the total number of beads in the tin can at first?
| |
Red beads |
Silver beads |
| Before |
1x5 =
5 u |
4x5 =
20 u |
| Change |
- 5 u |
- 7 u |
| After |
0 |
52 |
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 5 is 5.
Number of silver beads in the end
= 20 u - 7 u
= 13 u
13 u = 52
1 u = 52 ÷ 13 = 4
Total number of beads in the tin can at first
= 5 u + 20 u
= 25 u
= 25 x 4
= 100
Answer: 100
