PSLE At first, a box contained 55 yellow marbles and some silver beads. After some yellow marbles were removed,
35 of the marbles were silver. After 39 blue marbles were added to the box and now,
38 of the beads were silver. What was the number of yellow marbles removed?
|
Silver marbles |
Yellow marbles |
Blue marbles |
Total |
Before |
3 u |
55 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
3 u |
2 u |
0 |
5 u |
Change 2 |
|
|
+ 39 |
+ 3 u |
After 2 |
3 u |
2 u |
3 u |
8 u |
Some yellow marbles were removed at first. However, when 39 blue marbles were added, the number of yellow marbles remains unchanged.
Number of blue marbles added
= 8 u - 5 u
= 3 u
3 u = 39
1 u = 39 ÷ 3 = 13
Number of yellow marbles removed
= 55 - 2 u
= 55 - 2 x 13
= 55 - 26
= 29
Answer(s): 29