\(\dfrac{3}{4}=\dfrac{12}{16}\\ \dfrac{2}{3}=\dfrac{8}{12}\\ \dfrac{16}{20}=\dfrac{4}{5}\\ \dfrac{20}{50}=\dfrac{2}{5}\\ \dfrac{9}{21}=\dfrac{3}{7}\\ \)
`16/20=4/5`
`20/50=2/5`
`9/21=3/7`
`2/6=1/3`
`8/12=2/3`
`12/16=3/4`
`=> 3/4=12/16`
`2/3=8/12`
`2/5=20/50`
`3/7=9/21`
`2/3=8/12`