Fathers is three years older than mother
Brother is two years older than sister
Their ages added up is 73
Four years ago their ages added up to 58
Find the ages of each person in the family
If the sum of the 4 people's ages is 73, then 4 years ago, the sum would've been: 73 - 4(4), or 73 - 16 = 57, unless of course,
the youngest person was not born 4 years ago. That's what it is!
Let the father’s age, be F, and brother’s, B
Then mother’s is: F – 3, and sister’s is: B – 2
We then get: F + B + F – 3 + B – 2 = 73
2F + 2B – 5 = 73
2F + 2B = 78 ------- eq (i)
The youngest is the sister, so it appears that 4 years ago, she was not born so we get:
F – 4 + F – 3 – 4 + B – 4 = 58
2F + B – 15 = 58
2F + B = 73 ------- eq (ii)
B = 78 – 73 ------ Subtracting eq (ii) from eq (i)
B, or 
2F + 5 = 73 ------- Substituting 5 for B in eq (ii)
2F = 73 – 5
2F = 68
F, or 
