Yen is 3 years old. Her mother is 39 years old. How old will Yen be when her mother is four times her age?
| |
Yen |
Her mother |
Difference |
| Before |
3 |
39 |
36 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
4 u |
3 u |
The difference in the age between Yen and her mother remains unchanged.
Difference in their age at first
= 39 - 3
= 36
Difference in their age in the end
= 4 u - 1 u
= 3 u
3 u = 36
1 u = 36 ÷ 3 = 12
Yen's age when her mother is four times her age
= 1 u
= 12
Answer(s): 12
