Odpowiedź :
1)
[tex]\dfrac{3}{20}=\dfrac{3\cdot5}{20\cdot5}=\dfrac{15}{100}=\huge\boxed{\boxed{0,15}}[/tex]
2)
[tex]3\dfrac{4}{5}=3\dfrac{4\cdot2}{5\cdot2}=3\dfrac{8}{10}=\huge\boxed{\boxed{3,8}}[/tex]
3)
[tex]1\dfrac{3}{40}=1\dfrac{3\cdot25}{40\cdot25}=1\dfrac{75}{1000}=\huge\boxed{\boxed{1,075}}[/tex]