You can simplify a factor 2 in the first fraction:
[tex]\dfrac{2e}{2n} = \dfrac{e}{n}[/tex]
And you can ignore the ones in the second:
[tex]\dfrac{1w}{1n} = \dfrac{w}{n}[/tex]
If two fractions have the same denominator, you can sum the numerators:
[tex]\dfrac{e}{n}+\dfrac{w}{n} = \dfrac{e+w}{n}[/tex]
