You have the following ratio:
[tex]\frac{4}{5}[/tex]in order to determine an equivalent fraction, you take into account that the equivalent fraction is the fraction, which simplified, is the same fraction 4/5
In this case you can notice that if you simplify the fraction 16/20, you obtain
[tex]\frac{16}{20}=\frac{8}{10}=\frac{4}{5}[/tex]As you can notice, the simplified fraction is the same fraction 4/5.
Hence 16/20 is equivalent to 4/5