When Eva was 47 years old, her daughter was 3 times her son's age. Eva would be twice her daughter's age when her son was 37 years old. How old would Eva be when her son was 15 years old?
|
Eva |
Daughter |
Son |
Before |
47 |
3 u |
1 u |
Change |
+ ? |
+ ? |
+ ? |
After |
2 p |
1 p |
37 |
The difference in the ages between Eva and her daughter remains unchanged.
Difference in Eva's and her daughter's ages at first
47 - 3 u = 2 p - 1 p
47 - 3 u =
1 p --- (1)
The difference in the ages between her daughter and her son remains unchanged.
Difference in her daughter's and her son's ages at first
3 u - 1 u = 1 p - 37
2 u + 37 =
1 p --- (2)
Make p the same.
(1) = (2)
47 - 3 u = 2 u + 37
2 u + 3 u = 47 - 37
5 u = 10
1 u = 10 ÷ 5 = 2
Age difference between Eva and her son
= 47 - 1 u
= 47 - 2
= 45
Eva's age when her son was 15 years old
= 45 + 15
= 60
Answer(s): 60