At first, Ken had 129 more gold beads than black beads in a box. Each day, he took out 10 gold beads and 3 black beads from the box. After some time, he only had 39 black beads left in the box.
- How many beads did Ken take out from the box altogether?
- How many black beads did Ken have at first?
| |
Gold beads |
Black beads |
Comparing gold beads
and black beads at first |
129 more |
|
| Before |
10 u |
3 u + 39 |
| Change |
- 10 u |
- 3 u |
| After |
0 |
39 |
(a)
If another 129 black beads are added into the box at first, the number of gold and black beads will be the same.
10 u = 3 u + 39 + 129
10 u - 3 u = 39 + 129
7 u = 168
1 u = 168 ÷ 7 = 24
Number of beads that Ken took out
= 10 u + 3 u
= 13 u
= 13 x 24
= 312
(b)
Number of beads that Ken had at first
= 312 + 39
= 351
Answer(s): (a) 312; (b) 351
