Question 28714
EQuation is:
let x be the age
{{{1x/6+1x/12+1x/7+5+4=1x/2}}} ---> multiply the whole equation by 84
{{{84(1x/6)+84(1x/12)+84(1x/7)+84(5/1)+84(4/1)=84(1x/2)}}}
14x+7x+12x+420+336=42x
33x+756=42x
9x=756
x=84


Hence, he lived for 84 years.
Paul.