Question 976565
Bob's father is 3 times old as Bob. 4 years ago, he was 4 times older. How old is Bob?	
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let x=bob's age
3x= father's age
..
4 yrs ago:
x-4=bob's age
3x-4= father's age
3x-4=4(x-4) (4 years ago,father was 4 times older)
3x-4=4x-16
x=12
How old is Bob? 12