Tim is 7 years old. His father is 40 years older than him. In how many years will Tim's father be 3 times as old as Tim?
| |
His father |
Tim |
Difference |
| Before |
47 |
7 |
40 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Tim and his father at first and in the end remains the same.
Difference in the age between Tim and his father
= 3 u - 1 u
= 2 u
2 u = 40
1 u = 40 ÷ 2 = 20
The increase in age of Tim and his father remains the same.
Number of years' time so Tim's father will be 3 times as old as Tim
= 20 - 7
= 13
Answer(s): 13
