At first, David had 179 more white beads than black beads in a box. Each day, he took out 9 white beads and 2 black beads from the box. After some time, he only had 17 black beads left in the box.
- How many beads did David take out from the box altogether?
- How many black beads did David have at first?
| |
White beads |
Black beads |
Comparing white beads
and black beads at first |
179 more |
|
| Before |
9 u |
2 u + 17 |
| Change |
- 9 u |
- 2 u |
| After |
0 |
17 |
(a)
If another 179 black beads are added into the box at first, the number of white and black beads will be the same.
9 u = 2 u + 17 + 179
9 u - 2 u = 17 + 179
7 u = 196
1 u = 196 ÷ 7 = 28
Number of beads that David took out
= 9 u + 2 u
= 11 u
= 11 x 28
= 308
(b)
Number of beads that David had at first
= 308 + 17
= 325
Answer(s): (a) 308; (b) 325
