When Tina was 48 years old, her daughter was 5 times her son's age. Tina would be twice her daughter's age when her son was 30 years old. How old would Tina be when her son was 4 years old?

	Tina	Daughter	Son
Before	48	5 u	1 u
Change	+ ?	+ ?	+ ?
After	2 p	1 p	30

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

Difference in Tina's and her daughter's ages at first
48 - 5 u = 2 p - 1 p
48 - 5 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
5 u - 1 u = 1 p - 30
4 u + 30 = 1 p --- (2)

Make p the same.

(1) = (2)
48 - 5 u = 4 u + 30
4 u + 5 u = 48 - 30
9 u = 18

1 u = 18 ÷ 9 = 2

Age difference between Tina and her son
= 48 - 1 u
= 48 - 2
= 46

Tina's age when her son was 4 years old
= 46 + 4
= 50

Answer(s): 50