deletions | additions       diff --git a/untitled.tex b/untitled.tex  index 8b40e79..597d4af 100644  --- a/untitled.tex  +++ b/untitled.tex 
...
$\hspace{1cm}$ $1 $\_$ 2 $\_$ 3 $\_$ 4 $\_$ 5 $\_$ 6 $\_$ 7 $\_$ 8 $\_$ 9$  In this case, we find that such a construction is not possible. Here, we have $5$ odd numbers and therefore the total must be odd. Since $20$ is even, this proves it cannot be done.