Question 7663
This kind of indeterminate problem usually has constraints. I will use: what is the smallest amount he could have had.
We have the following information
{{{w/2+w/7+2w/3 +2000 = estate}}}
{{{21w/42+6w/42+28w/42+2000 = estate}}} 
{{{55w/42+2000=estate}}}
The issue now is to find an integer w that allows a solution. Obviously 42 will work.
The numerator of the distributions is then {{{55(42)=2310}}}
So he leaves 1/2 of that to his wife; {{{2310/2=1155}}}
He leaves 1/7 of that to his son; {{{2310/7=330}}}
He leaves 2/3 of that to his servant {{{4620/3=1540}}}
So his total estate was {{{1155+330+1540+2000=5025}}}

[Since I hate these kinds of problems, someone should check my logic carefully.]