Ivan is 9 years old. His father is 36 years older than him. In how many years will Ivan's father be 3 times as old as Ivan?
| |
His father |
Ivan |
Difference |
| Before |
45 |
9 |
36 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Ivan and his father at first and in the end remains the same.
Difference in the age between Ivan and his father
= 3 u - 1 u
= 2 u
2 u = 36
1 u = 36 ÷ 2 = 18
The increase in age of Ivan and his father remains the same.
Number of years' time so Ivan's father will be 3 times as old as Ivan
= 18 - 9
= 9
Answer(s): 9
