a)
[tex]\dfrac{75}{100}=\dfrac{75:25}{100:25}=\boxed{\frac{3}{4}}[/tex]
b)
[tex]\dfrac{170}{340}=\dfrac{170:170}{340:170}=\boxed{\frac{1}{2}}[/tex]
c)
[tex]\dfrac{27}{81}=\dfrac{27:27}{81:27}=\boxed{\frac{1}{3}}[/tex]
d)
[tex]\dfrac{4}{8}=\dfrac{4:4}{8:4}=\boxed{\frac{1}{2}}[/tex]
