Question 1006068
Not as you wrote since that would be useless having  {{{x/x}}}, but as you must have been given, {{{C(x)=(250+4x)/x}}}.  You want to find inverse of C(x).


Let I(x) be the inverse of C(x).  
{{{C(I(x))=(250+4(I(x)))/I(x)=x}}}


{{{250+4I(x)=x*I(x)}}}


{{{x*I(x)-4*I(x)=250}}}


{{{(x-4)I(x)=250}}}


{{{highlight(I(x)=250/(x-4))}}}



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You originally show  250+4x/x  in pure text, which correctly rendered is  {{{250+4x/x}}} simplifiable to {{{250+4*1=254}}}, and is not what you really want.  THAT shows a useless as well as wrong factor of  {{{x/x}}}.