In a tin can, the ratio of the number of gold balls to the number of blue balls was 1 : 3. Each time, 3 gold and 6 blue balls were taken out of the tin can. A while later, only 171 blue balls were left in the tin can. What was the total number of balls in the tin can at first?
| |
Gold balls |
Blue balls |
| Before |
1x3 =
3 u |
3x3 =
9 u |
| Change |
- 3 u |
- 6 u |
| After |
0 |
171 |
Since there is no gold balls left, this means that the number of gold marbles at first is the same as the number of gold marbles taken out.
Make the number of gold balls at first and taken out the same. LCM of 1 and 3 is 3.
Number of blue balls in the end
= 9 u - 6 u
= 3 u
3 u = 171
1 u = 171 ÷ 3 = 57
Total number of balls in the tin can at first
= 3 u + 9 u
= 12 u
= 12 x 57
= 684
Answer: 684
