Bryan is 20 years old. The total age of Bryan and Adam is 80 years. How many years' time will the ratio of Bryan's age to Adam's age be 3 : 7?
|
Bryan |
Adam |
Total |
Difference |
Before |
20 |
60 |
80 |
40 |
Change |
+ ? |
+ ? |
|
|
After |
3 u |
7 u |
|
4 u |
Adam's age
= 80 - 20
= 60
Difference in the age between Bryan and Adam
= 60 - 20
= 40
Difference in the age between Bryan and Adam in units
= 7 u - 3 u
= 4 u
4 u = 40
1 u = 40 ÷ 4 = 10
Bryan's age now = 20
Bryan's age after = 3 u = 3 x 10 = 30
Number of years' time
= 30 - 20
= 10
Answer(s): 10