PSLE
At first, a container contained 2 white marbles and some gold beads. After some white marbles were added, 35 of the marbles were gold. After 50 green marbles were added to the container and now, 310 of the beads were gold. What was the number of white marbles added?
|
Gold marbles |
White marbles |
Green marbles |
Total |
Before |
3 u |
2 |
0 |
|
Change 1 |
|
+ ? |
|
+ ? |
After 1 |
3 u |
2 u |
0 |
5 u |
Change 2 |
|
|
+ 50 |
+ 5 u |
After 2 |
3 u |
2 u |
5 u |
10 u |
Some white marbles were added at first. However, when 50 green marbles were added, the number of white marbles remains unchanged.
Number of green marbles added
= 10 u - 5 u
= 5 u
5 u = 50
1 u = 50 ÷ 5 = 10
Number of white marbles added
= 2 u - 2
= 2 x 10 - 2
= 20 - 2
= 18
Answer(s): 18