At first, David had 131 more purple beads than silver beads in a box. Each day, he took out 7 purple beads and 3 silver beads from the box. After some time, he only had 37 silver beads left in the box.
- How many beads did David take out from the box altogether?
- How many silver beads did David have at first?
| |
Purple beads |
Silver beads |
Comparing purple beads
and silver beads at first |
131 more |
|
| Before |
7 u |
3 u + 37 |
| Change |
- 7 u |
- 3 u |
| After |
0 |
37 |
(a)
If another 131 silver beads are added into the box at first, the number of purple and silver beads will be the same.
7 u = 3 u + 37 + 131
7 u - 3 u = 37 + 131
4 u = 168
1 u = 168 ÷ 4 = 42
Number of beads that David took out
= 7 u + 3 u
= 10 u
= 10 x 42
= 420
(b)
Number of beads that David had at first
= 420 + 37
= 457
Answer(s): (a) 420; (b) 457
