(2 1/2 + 0,25 ) - (1/4 - 4,25 + 1/2 )

  (2$\dfrac{1}{2}$ + 0,25) - ($\dfrac{1}{4}$ - 4,25 + $\dfrac{1}{2}$ )

= ($\dfrac{5}{2}$ + $\dfrac{1}{4}$) - ($\dfrac{1}{4}$ - $\dfrac{17}{4}$ + $\dfrac{1}{2}$ )

= $\dfrac{5}{2}$ + $\dfrac{1}{4}$ - $\dfrac{1}{4}$ + $\dfrac{17}{4}$ - $\dfrac{1}{2}$ 

= ($\dfrac{1}{4}$ - $\dfrac{1}{4}$ + $\dfrac{17}{4}$) + ($\dfrac{5}{2}$ - $\dfrac{1}{2}$)

= $\dfrac{17}{4}$ + 2

= $\dfrac{17}{4}$ + $\dfrac{8}{4}$

= $\dfrac{17+8}{4}$

= $\dfrac{25}{4}$

= 6,25