Equivalent fractions are fractions which have the same value. They are obtained by multiplying both the numerator and the denominator of a fraction by the same number.

$\frac{4}{5}=\frac{4\times 3}{5\times 3}=\frac{12}{15}$

$\frac{4}{5}=\frac{4\times 5}{5\times 5}=\frac{20}{25}$

Hence, $\frac{4}{5}$ is equivalent to $\frac{12}{15}$ and $\frac{20}{25}$.