SOLUTION: Two years ago, my age was four times that of my son. Eight years ago, my age was ten times that of my son. Find the age of my son now.

Algebra ->  Equations -> SOLUTION: Two years ago, my age was four times that of my son. Eight years ago, my age was ten times that of my son. Find the age of my son now.      Log On


   

Question 772462: Two years ago, my age was four times that of my son. Eight years ago, my age was ten times that of my son. Find the age of my son now.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +f+ = my age now
Let +s+ = my son's age now
+f+-+2+ = my age 2 yrs ago
+s+-+2+ = my son's age 2 yrs ago
+f+-+8+ = my age 8 yrs ago
+s+-+8+ = my son's age 8 yrs ago
------------------------------
(1) +f-2+=+4%2A%28+s-2+%29+
(2) +f-8+=+10%2A%28+s-8+%29+
---------------------
(1) +f+-+2+=+4s+-+8+
(1) +f+-+4s+=+-6+
and
(2) +f+-+8+=+10s+-+80+
(2) +f+-+10s+=+-72+
-------------------
Subtract (2) from (1)
(1) +f+-+4s+=+-6+
(2) +-f+%2B+10s+=+72+
+6s+=+66+
+s+=+11+
Plug this result back into either equation
(1) +f-2+=+4%2A%28+11-2+%29+
(1) +f+-+2+=+36+
(1) +f+=+38+
My son is 11 now
check:
(2) +38-8+=+10%2A%28+11-8+%29+
(2) +30+=+10%2A3+
(2) +30+=+30+
OK