PSLE At first, a container contained 76 yellow balls and some grey beads. After some yellow balls were removed,
38 of the balls were grey. After 42 purple balls were added to the container and now,
314 of the beads were grey. What was the number of yellow balls removed?
|
Grey balls |
Yellow balls |
Purple balls |
Total |
Before |
3 u |
76 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
3 u |
5 u |
0 |
8 u |
Change 2 |
|
|
+ 42 |
+ 6 u |
After 2 |
3 u |
5 u |
6 u |
14 u |
Some yellow balls were removed at first. However, when 42 purple balls were added, the number of yellow balls remains unchanged.
Number of purple balls added
= 14 u - 8 u
= 6 u
6 u = 42
1 u = 42 ÷ 6 = 7
Number of yellow balls removed
= 76 - 5 u
= 76 - 5 x 7
= 76 - 35
= 41
Answer(s): 41