Adam has 80 red marbles and 200 blue marbles.
After buying the same number of marbles,
the ratio of the red marbles and the blue marbles becomes 3 : 5.
How many marbles does he buy?
|
Red |
Blue |
Difference |
Before |
80 |
200 |
120 |
Change |
+ ? |
+ ? |
|
After |
3 u |
5 u |
2 u |
At first
Difference in the number of marbles
= 200 - 80
= 120
In the end
Number of red marbles = 3 u
Number of blue marbles = 5 u
Difference in the number of marbles in units
= 5 u - 3 u
= 2 u
The difference in the number of marbles between the red marbles and the blue marbles remains unchanged.
2 u = 120
1 u = 120 ÷ 2 = 60
Number of red marbles that Adam buys
= 3 u - 80
= 3 x 60 - 80
= 180 - 80
= 100
Total number of marbles that Adam buys
= 2 x 100
= 200
Answer(s): 200