There are some brown and silver beads in a box. If 5 brown beads are removed from the box, the total number of beads left will be 7 times the number of brown beads left. If 18 silver beads are removed from the box, the total number of beads left will be 3 times the number of brown beads. How many beads are there in the box?
|
Case 1 |
Case 2 |
|
Brown beads |
Silver beads |
Brown beads |
Silver beads |
Before |
1 u + 5 |
6 u |
1 p |
2 p + 18 |
Change |
- 5 |
|
|
- 18 |
After |
1 u |
6 u |
1 p |
2 p |
Number of silver beads in the end for Case 1
= 7 u - 1 u
= 6 u
Number of brown beads in the end for Case 2
= 3 p - 1 p
= 2 p
The number of brown beads at first is the same for Case 1 and Case 2.
The number of silver beads at first is also the same for Case 1 and Case 2.
1 u + 5 = 1 p --- (1)
6 u = 2 p + 18
6 u - 18 =
2 p --- (2)
Make p the same.
(1)
x2 2 u + 10 =
2 p --- (3)
(2) = (3)
6 u - 18 = 2 u + 10
6 u - 2 u = 10 + 18
4 u = 28
1 u = 28 ÷ 4 = 7
Number of beads in the box
= (1 u + 5) + 6 u
= 7 u + 5
= (7 x 7) + 5
= 49 + 5
= 54
Answer(s): 54