Answer :

[tex]-5 \dfrac{1}{4} - (-7 \dfrac{1}{2} ) = -5 \dfrac{1}{4} + 7 \dfrac{1}{2} =-5 \dfrac{1}{4} + 7 \dfrac{2}{4} = 7 \dfrac{2}{4} -5 \dfrac{1}{4} =2 \dfrac{1}{4}[/tex]