Adam has 30 blue beads and 210 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 |
30 |
210 |
180 |
Change |
+ ? |
+ ? |
|
After |
3 u |
7 u |
4 u |
At first
Difference in the number of beads
= 210 - 30
= 180
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 = 180
1 u = 180 ÷ 4 = 45
Number of blue beads that Adam buys
= 3 u - 30
= 3 x 45 - 30
= 135 - 30
= 105
Total number of beads that Adam buys
= 2 x 105
= 210
Answer(s): 210