SOLUTION: a father is four times as old as his son. In 6 years time their combined ages will be 57. How old is the father.

Algebra ->  Human-and-algebraic-language -> SOLUTION: a father is four times as old as his son. In 6 years time their combined ages will be 57. How old is the father.      Log On


   

Question 497638: a father is four times as old as his son. In 6 years time their combined ages will be 57. How old is the father.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let f = Father's age
Let s = Son's age
given:
(1) +f+=+4s+
(2) +f+%2B+6+%2B+s+%2B+6+=+57+
-------------------
(1) +s+=+f%2F4+
By substitution,
(2) +f+%2B+6+%2B+f%2F4+%2B+6+=+57+
Multiply both sides by 4
(2) +4f+%2B+24+%2B+f+%2B+24+=+228+
(2) +5f+=+228+-+48+
(2) +5f+=+180+
(2) +f+=+36+
The Father is 36
----------------
check answer:
(1) +s+=+f%2F4+
(1) +s+=+36%2F4+
(1) +s+=+9+
and
(2) +f+%2B+6+%2B+s+%2B+6+=+57+
(2) +36+%2B+6+%2B+9+%2B+6+=+57+
(2) +42+%2B+15+=+57+
(2) +57+=+57+
OK