In a bottle, the ratio of the number of pink beads to the number of white beads was 1 : 4. Each time, 5 pink and 7 white beads were taken out of the bottle. A while later, only 91 white beads were left in the bottle. What was the total number of beads in the bottle at first?
| |
Pink beads |
White beads |
| Before |
1x5 =
5 u |
4x5 =
20 u |
| Change |
- 5 u |
- 7 u |
| After |
0 |
91 |
Since there is no pink beads left, this means that the number of pink marbles at first is the same as the number of pink marbles taken out.
Make the number of pink beads at first and taken out the same. LCM of 1 and 5 is 5.
Number of white beads in the end
= 20 u - 7 u
= 13 u
13 u = 91
1 u = 91 ÷ 13 = 7
Total number of beads in the bottle at first
= 5 u + 20 u
= 25 u
= 25 x 7
= 175
Answer: 175
