SOLUTION: A man is twice as old as his son. His son is twice as old as his sister. The total age is 84. What is the father's age?

Question 560466: A man is twice as old as his son. His son is twice as old as his sister. The total age is 84. What is the father's age?
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A man is twice as old as his son. His son is twice as old as his sister. The total age is 84. What is the father's age?
-------------------
Equations:
m = 2s
s = 2S
-----
m + s + S = 84
2s + s + (s/2) = 84
---
(7/2)s = 84
(1/2)s = 12
s = 24 yrs (son's age)
m = 2s = 48 (man's age)
S = s/2 = 12 (sister's age)
===============================
Cheers,
Stan H.

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = Son's age
Let = Sister's age
Let = Father's age
given:
(1)
(2)
(3)
---------------
This is 3 equations and 3 unknowns, so it's solvable
(2)
Substitute (1) and (2) into (3)
(3)

and

and

The Father is 48, the Son is 24, and the Sister is 12
check:
(3)
(3)
(3)
OK
RELATED QUESTIONS
A man is twice as old as his son. His son is twice as old as his sister. Their total ages (answered by ramkikk66)
A father is twice as old as his son. He was 6 times his son�s age 20 years ago. What is... (answered by Cromlix)
A father is twice as old as his son. He was 6 times his son�s age 20 years ago. What is... (answered by Boreal,Alan3354)
a father is twice as old as his son..20 years before,the father was four times as old as... (answered by Narsinghchauhan8960103366)
A man is 24 older than his son.Eight years ago, he was twice as old as his son. Calculate (answered by math_helper)
A man is twice as old as his son, and 4 years older than his wife. Their ages total 111... (answered by Fombitz)
Word Problems A man is twice as old as his son. His son is twice as old as his sister.... (answered by ikleyn,josgarithmetic)
A man is twice as old as his son. Ten years ago, he was thrice as old as the son. what is (answered by LinnW)
A father is twice as old as his son 12 years ago the father was 4 times as old as the son (answered by anukamal)