Adam has 40 blue beads and 140 red beads.
After buying the same number of beads,
the ratio of the blue beads and the red beads becomes 3 : 7.
How many beads does he buy?
|
Blue |
Red |
Difference |
Before |
40 |
140 |
100 |
Change |
+ ? |
+ ? |
|
After |
3 u |
7 u |
4 u |
At first
Difference in the number of beads
= 140 - 40
= 100
In the end
Number of blue beads = 3 u
Number of red beads = 7 u
Difference in the number of beads in units
= 7 u - 3 u
= 4 u
The difference in the number of beads between the blue beads and the red beads remains unchanged.
4 u = 100
1 u = 100 ÷ 4 = 25
Number of blue beads that Adam buys
= 3 u - 40
= 3 x 25 - 40
= 75 - 40
= 35
Total number of beads that Adam buys
= 2 x 35
= 70
Answer(s): 70