SOLUTION: BOB'S FATHER AGE IS 3 TIMES OLD AS BOB.4 YEARS AGO,HE WAS 4 TIMES OLDER.HOW OLD IS BOB?

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Question 150712: BOB'S FATHER AGE IS 3 TIMES OLD AS BOB.4 YEARS AGO,HE WAS 4 TIMES OLDER.HOW OLD IS BOB?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
B - Bob's age
F- Bob's father's age
1.F=3B
Four years ago, Bob was B-4 years old and his father was F-4.
2.F-4=4%28B-4%29
Now you have two equations with two unknowns, you can solve it.
Substitute eq. 1 into eq. 2 and solve for B.
2.F-4=4%28B-4%29
3B-4=4%28B-4%29
3B-4=4B-16
-B=-12
B=12
Now use equation 1 to solve for F.
1.F=3B
F=3%2812%29
F=36
Bob is 12 and his father is 36.
Four years ago, Bob was 8 and his father was 32.