PSLE At first, a box contained 93 black beads and some blue beads. After some black beads were removed,
47 of the beads were blue. After 84 brown beads were added to the box and now,
413 of the beads were blue. What was the number of black beads removed?
|
Blue beads |
Black beads |
Brown beads |
Total |
Before |
4 u |
93 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
4 u |
3 u |
0 |
7 u |
Change 2 |
|
|
+ 84 |
+ 6 u |
After 2 |
4 u |
3 u |
6 u |
13 u |
Some black beads were removed at first. However, when 84 brown beads were added, the number of black beads remains unchanged.
Number of brown beads added
= 13 u - 7 u
= 6 u
6 u = 84
1 u = 84 ÷ 6 = 14
Number of black beads removed
= 93 - 3 u
= 93 - 3 x 14
= 93 - 42
= 51
Answer(s): 51