In a jar, the ratio of the number of gold balls to the number of brown balls was 1 : 3. Each time, 3 gold and 6 brown balls were taken out of the jar. A while later, only 117 brown balls were left in the jar. What was the total number of balls in the jar at first?
| |
Gold balls |
Brown balls |
| Before |
1x3 =
3 u |
3x3 =
9 u |
| Change |
- 3 u |
- 6 u |
| After |
0 |
117 |
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 brown balls in the end
= 9 u - 6 u
= 3 u
3 u = 117
1 u = 117 ÷ 3 = 39
Total number of balls in the jar at first
= 3 u + 9 u
= 12 u
= 12 x 39
= 468
Answer: 468
