When Mr Mark is 23 years old, his cousin is 2 years old. In how many years will he be 4 times as old as his cousin?
|
Mr Mark |
His cousin |
Difference |
Before |
23 |
2 |
21 |
Change |
+ ? |
+ ? |
|
After |
4 u |
1 u |
3 u |
The difference in the age between Mr Mark and his cousin at first and in the end remains the same.
Difference in the age between Mr Mark and his cousin
= 4 u - 1 u
= 3 u
3 u = 23 - 2
3 u = 21
1 u = 21 ÷ 3 = 7
Number of years' time so Mr Mark will be 4 times as old as his cousin
= 7 - 2
= 5
Answer(s): 5