Question 848238
This is simply a matter of arithmetic, and maybe differences among equivalent forms.


You want f(x)+g(x).


Assuming you are missing certain parentheses, I am using them.
{{{2/x+4/(x+4)}}}
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Simplest common denominator is {{{x(x+4)}}}.
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{{{(2/x)((x+4)/(x+4))+(4/(x+4))(x/x)}}}
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{{{(2(x+4))/(x(x+4))+4x/(x(x+4))}}}
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{{{(2x+8)/(x(x+4))+4x/(x(x+4))}}}
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{{{(2x+4x+8)/(x(x+4))}}}
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{{{(6x+8)/(x^2+4x)}}}