Adam has 20 green beads and 240 red beads.
After buying the same number of beads,
the ratio of the green beads and the red beads becomes 3 : 7.
How many beads does he buy?
|
Green |
Red |
Difference |
Before |
20 |
240 |
220 |
Change |
+ ? |
+ ? |
|
After |
3 u |
7 u |
4 u |
At first
Difference in the number of beads
= 240 - 20
= 220
In the end
Number of green 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 green beads and the red beads remains unchanged.
4 u = 220
1 u = 220 ÷ 4 = 55
Number of green beads that Adam buys
= 3 u - 20
= 3 x 55 - 20
= 165 - 20
= 145
Total number of beads that Adam buys
= 2 x 145
= 290
Answer(s): 290