Ian is 7 years old now. His sister is 18 years older than him. How old will Ian be when his age is
25 of his sister's age?
| |
Ian |
His sister |
Difference |
| Before |
|
|
18 |
| Change |
+ ? |
+ ? |
|
| After |
2 u |
5 u |
3 u |
The difference in the age between Ian and his sister at first and in the end remains unchanged.
Number of years that his sister is older than Ian
= 5 u - 2 u
= 3 u
3 u = 18
1 u = 18 ÷ 3 = 6
Ian's age when his age is
25 of his sister's age
= 2 u
= 2 x 6
= 12
Answer(s): 12
