Question 27432
Let x be his age:
After = + and 5 years after means that add 5 to current status:
1x/6+1x/12+1x/7+5+4=1x/2
Common denominator = 84
14x+7x+12x+420+336=42x
Simplfy
33x+756=42x
9x=756
x=84


Hence, he lived for 84 years.
Paul.