Adam has 70 green marbles and 220 red marbles.
After buying the same number of marbles,
the ratio of the green marbles and the red marbles becomes 3 : 8.
How many marbles does he buy?
|
Green |
Red |
Difference |
Before |
70 |
220 |
150 |
Change |
+ ? |
+ ? |
|
After |
3 u |
8 u |
5 u |
At first
Difference in the number of marbles
= 220 - 70
= 150
In the end
Number of green marbles = 3 u
Number of red marbles = 8 u
Difference in the number of marbles in units
= 8 u - 3 u
= 5 u
The difference in the number of marbles between the green marbles and the red marbles remains unchanged.
5 u = 150
1 u = 150 ÷ 5 = 30
Number of green marbles that Adam buys
= 3 u - 70
= 3 x 30 - 70
= 90 - 70
= 20
Total number of marbles that Adam buys
= 2 x 20
= 40
Answer(s): 40