Mr Bobby is 2 times as old as his son, Archie. 20 years ago, the ratio in the age of Mr Bobby and Archie was 10 : 3. Find Mr Bobby's current age.
| |
Mr Bobby |
Archie |
Difference |
| Before |
10x1 =
10 u |
3x1 =
3 u |
7x1 =
7 u |
| Change |
+ 20 |
+ 20 |
|
| After |
2x7 =
14 u |
1x7 =
7 u |
1x7 =
7 u |
The difference in the age of Mr Bobby and Archie at first and in the end remains unchanged. Make the difference in age the same. LCM of 7 and 1 is 7.
The increase in the age of Mr Bobby and Archie is the same.
Increase in Archie's age
= 7 u - 3 u
= 4 u
4 u = 20
1 u = 20 ÷ 4 = 5
Mr Bobby's current age
= 14 u
= 14 x 5
= 70
Answer(s): 70
