In a jar, the ratio of the number of brown balls to the number of blue balls was 1 : 3. Each time, 3 brown and 7 blue balls were taken out of the jar. A while later, only 114 blue balls were left in the jar. What was the total number of balls in the jar at first?
| |
Brown balls |
Blue balls |
| Before |
1x3 =
3 u |
3x3 =
9 u |
| Change |
- 3 u |
- 7 u |
| After |
0 |
114 |
Since there is no brown balls left, this means that the number of brown marbles at first is the same as the number of brown marbles taken out.
Make the number of brown balls at first and taken out the same. LCM of 1 and 3 is 3.
Number of blue balls in the end
= 9 u - 7 u
= 2 u
2 u = 114
1 u = 114 ÷ 2 = 57
Total number of balls in the jar at first
= 3 u + 9 u
= 12 u
= 12 x 57
= 684
Answer: 684
