Question 1094365
.
<U>First part of my answer</U>.


<pre>
    If it is  

    {{{1/x + 1/(x+1)}}} = {{{9/20}}}

    then, after multiplying both sides by x*(x+1), you have

    20*(x+1) + 20*x = 9x*(x+1)  ====>  20x + 20 + 20x = 9x^2 + 9x  ====>

    9x^2 - 31x - 20 = 0  ====>  after factoring the left side ====>  

    (9x+5)*(x-4) = 0  ====>  the solutions are   x = {{{-5/9}}}  and  x = 4.
</pre>


<U>Second part of my answer</U>



Your formula is ambiguous and unreadable without using parentheses.


<pre>
     Is it   (1/x) + (1/x) + 1 = (9/20)    or   (1/x) + (1/(x+1)) = 9/20  ??
</pre>

Use parentheses to make your formulas readable and unambiguous.



Use parentheses when you post your formulas to this forum.



It is the &nbsp;<U>REQUIREMENT</U>&nbsp; of this site.



There is &nbsp;<U>NO OTHER WAY</U>&nbsp;  to make them readable and unambiguous.



By &nbsp;<U>violating</U>&nbsp; this &nbsp;<U>RULE</U>, &nbsp;you work &nbsp;<U>against yourself</U>&nbsp; and &nbsp;<U>against your better interests</U>.



With it, &nbsp;welcome to the forum !!



---------------
I repeat this mantra to each and every new visitor coming to this forum,

until he or she will take it seriously.
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<pre>
    Once, when I sent this message to some customer/"student"/visitor, he responded me (through the "Thank you" form),
    asking why he (or she ?) should use parentheses when his source (textbook, teacher's assignment sheet and so on)
    does not contain these parentheses ?
</pre>

Good question ! 


<pre>
     The answer is: That sources have <U>TYPOGRAPHY MEANS</U> to represent the fractions, writing them in two levels /
     numerators and denominators, divided by horizontal lines.

     Such typography tools <U>ABSENT</U> in this forum, <U>THEREFORE</U> the customers <U>SHOULD</U> write parentheses to present numerators and denominators
     explicitly.
</pre>


Hope this explanation makes this issue absolutely clear.