Cześć!
Od a) do c)
[tex]2,7+(-6,9)=2,7-6,9=-(6,9-2,7)=-4,2\\\\-3\frac{2}{3}+(-2\frac{3}{5})=-(3\frac{2}{3}+2\frac{3}{5})=-(3\frac{10}{15}+2\frac{9}{15})=-5\frac{19}{15}=-6\frac{4}{15}\\\\-3,5+2\frac{1}{5}=-3,5+2\frac{2}{10}=-3,5+2,2=-(3,5-2,2)=-1,3[/tex]
Od d) do f)
[tex]4,5-7,9=-(7,9-4,5)=-3,4\\\\1\frac{5}{6}-(-2\frac{2}{3})=1\frac{5}{6}+2\frac{2}{3}=1\frac{5}{6}+2\frac{4}{6}=3\frac{9}{6}=4\frac{3}{6}=4\frac{1}{2}\\\\-4\frac{2}{7}-6\frac{1}{5}=-(4\frac{2}{7}+6\frac{1}{5})=-(4\frac{10}{35}+6\frac{7}{35})=-10\frac{17}{35}[/tex]
