Bobby is 6 years old now. His sister is 18 years older than him. How old will Bobby be when his age is
57 of his sister's age?
| |
Bobby |
His sister |
Difference |
| Before |
|
|
18 |
| Change |
+ ? |
+ ? |
|
| After |
5 u |
7 u |
2 u |
The difference in the age between Bobby and his sister at first and in the end remains unchanged.
Number of years that his sister is older than Bobby
= 7 u - 5 u
= 2 u
2 u = 18
1 u = 18 ÷ 2 = 9
Bobby's age when his age is
57 of his sister's age
= 5 u
= 5 x 9
= 45
Answer(s): 45
