At first, Billy had 108 more brown beads than black beads in a box. Each day, he took out 5 brown beads and 2 black beads from the box. After some time, he only had 24 black beads left in the box.
- How many beads did Billy take out from the box altogether?
- How many black beads did Billy have at first?
| |
Brown beads |
Black beads |
Comparing brown beads
and black beads at first |
108 more |
|
| Before |
5 u |
2 u + 24 |
| Change |
- 5 u |
- 2 u |
| After |
0 |
24 |
(a)
If another 108 black beads are added into the box at first, the number of brown and black beads will be the same.
5 u = 2 u + 24 + 108
5 u - 2 u = 24 + 108
3 u = 132
1 u = 132 ÷ 3 = 44
Number of beads that Billy took out
= 5 u + 2 u
= 7 u
= 7 x 44
= 308
(b)
Number of beads that Billy had at first
= 308 + 24
= 332
Answer(s): (a) 308; (b) 332
