1/2 - 5/11 + 7/2 - 9/11 =
= (1/2 + 7/2) - (5/11 + 9/11)
= 8/2 - 14/11
= ¹¹⁾4 - 14/11
= (44 - 14)/11
= 30/11
= 2 8/11
[tex]\it \dfrac{1}{2}-\dfrac{5}{11}+\dfrac{7}{2}-\dfrac{9}{11}=(\dfrac{1}{2}+\dfrac{7}{2})-(\dfrac{5}{11}+\dfrac{9}{11}) =\dfrac{8}{2}-\dfrac{14}{11}=4-1\dfrac{3}{11}=\\ \\ \\ =3\dfrac{11}{11}-1\dfrac{3}{11}=2\dfrac{8}{11}[/tex]
