When Lynn was 47 years old, her daughter was 2 times her son's age. Lynn would be twice her daughter's age when her son was 35 years old. How old would Lynn be when her son was 9 years old?

	Lynn	Daughter	Son
Before	47	2 u	1 u
Change	+ ?	+ ?	+ ?
After	2 p	1 p	35

The difference in the ages between Lynn and her daughter remains unchanged.

Difference in Lynn's and her daughter's ages at first
47 - 2 u = 2 p - 1 p
47 - 2 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
2 u - 1 u = 1 p - 35
1 u + 35 = 1 p --- (2)

Make p the same.

(1) = (2)
47 - 2 u = 1 u + 35
1 u + 2 u = 47 - 35
3 u = 12

1 u = 12 ÷ 3 = 4

Age difference between Lynn and her son
= 47 - 1 u
= 47 - 4
= 43

Lynn's age when her son was 9 years old
= 43 + 9
= 52

Answer(s): 52