Answer
$\dfrac{13x}{20}$
Work Step by Step
Make the rational expressions similar by using their LCD of $20$ to obtain:
$\dfrac{2x}{5}+\dfrac{x}{4}
\\=\dfrac{2x\color{magenta}{(4)}}{5\color{magenta}{(4)}}+\dfrac{x\color{magenta}{(5)}}{4\color{magenta}{(5)}}
\\=\dfrac{8x}{20}+\dfrac{5x}{20}
\\=\dfrac{8x+5x}{20}
\\=\dfrac{13x}{20}$
