PSLE At first, a box contained 63 brown marbles and some black beads. After some brown marbles were removed,
710 of the marbles were black. After 48 purple marbles were added to the box and now,
713 of the beads were black. What was the number of brown marbles removed?
|
Black marbles |
Brown marbles |
Purple marbles |
Total |
Before |
7 u |
63 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
7 u |
3 u |
0 |
10 u |
Change 2 |
|
|
+ 48 |
+ 3 u |
After 2 |
7 u |
3 u |
3 u |
13 u |
Some brown marbles were removed at first. However, when 48 purple marbles were added, the number of brown marbles remains unchanged.
Number of purple marbles added
= 13 u - 10 u
= 3 u
3 u = 48
1 u = 48 ÷ 3 = 16
Number of brown marbles removed
= 63 - 3 u
= 63 - 3 x 16
= 63 - 48
= 15
Answer(s): 15