Answer :
Usa la siguiente propiedad:
[tex]\begin{gathered} \frac{a}{c}+\frac{b}{c}=\frac{a+b}{c} \\ \frac{4}{10}+\frac{5}{10}=\frac{4+5}{10}=\frac{9}{10}=0.9 \end{gathered}[/tex][tex]\frac{3}{5}+\frac{6}{5}=\frac{3+6}{5}=\frac{9}{5}=1.8[/tex]Usa la siguiente propiedad:
[tex]\begin{gathered} \frac{a}{c}+\frac{b}{c}=\frac{a+b}{c} \\ \frac{4}{10}+\frac{5}{10}=\frac{4+5}{10}=\frac{9}{10}=0.9 \end{gathered}[/tex][tex]\frac{3}{5}+\frac{6}{5}=\frac{3+6}{5}=\frac{9}{5}=1.8[/tex]