Question 4084
Earlsdon set the problem up properly  but the common denominator was wrong:
The common denominator is not 24.  9 is not a multiple of 24
The common denominator IS 72 SO:  going back to the problem:


Let x = the inital value of the estate. 
x  -  (1/2)x  -  (3/9)x  -  (3/24)x = $18,000 
x  -  {{{36/72}}}x  -  {{{(3)(8)/72}}}x  -  {{{(3)(3)/72}}}x=18,000


Then
x  -  {{{36/72}}}x   -  {{{(24)/72}}}x  -  {{{(9)/72}}}x=18,000

x  -  {{{69/72}}}x=1800


Multiply everything by 72
(72)x  -  (72){{{69/72}}}x=1800(72)
72x-69x=129,600
3x=129,600
x=43,200


The value of his estate is $43,200