There are some white and red beads in a box. If 5 white beads are removed from the box, the total number of beads left will be 8 times the number of white beads left. If 45 red beads are removed from the box, the total number of beads left will be 3 times the number of white beads. How many beads are there in the box?
|
Case 1 |
Case 2 |
|
White beads |
Red beads |
White beads |
Red beads |
Before |
1 u + 5 |
7 u |
1 p |
2 p + 45 |
Change |
- 5 |
|
|
- 45 |
After |
1 u |
7 u |
1 p |
2 p |
Number of red beads in the end for Case 1
= 8 u - 1 u
= 7 u
Number of white beads in the end for Case 2
= 3 p - 1 p
= 2 p
The number of white beads at first is the same for Case 1 and Case 2.
The number of red beads at first is also the same for Case 1 and Case 2.
1 u + 5 = 1 p --- (1)
7 u = 2 p + 45
7 u - 45 =
2 p --- (2)
Make p the same.
(1)
x2 2 u + 10 =
2 p --- (3)
(2) = (3)
7 u - 45 = 2 u + 10
7 u - 2 u = 10 + 45
5 u = 55
1 u = 55 ÷ 5 = 11
Number of beads in the box
= (1 u + 5) + 7 u
= 8 u + 5
= (8 x 11) + 5
= 88 + 5
= 93
Answer(s): 93