Since you can directly sum two fractions with the same denominator, we can rearrange the sum as follows:
[tex] -\dfrac{7}{16} - \dfrac{5}{16} - \dfrac{1}{4} [/tex]
Now we can sum the first two fraction easily:
[tex] \dfrac{-7-5}{16} - \dfrac{1}{4} = \dfrac{-12}{16} - \dfrac{1}{4}[/tex]
We can simplify the first fraction: 12/16=3/4. So, we can sum the two fractions again because they have the same denominator:
[tex] \dfrac{-12}{16} - \dfrac{1}{4} = \dfrac{-3}{4} - \dfrac{1}{4} = \dfrac{-3-1}{4} = \dfrac{-4}{4} = -1[/tex]
