a)
$$0,2 = \frac{2}{10} = \frac{1}{5}$$
б)
$$0,88 = \frac{88}{100} = \frac{22}{25}$$
в)
$$0,64 = \frac{64}{100} = \frac{16}{25}$$
г)
$$0,256 = \frac{256}{1000} = \frac{32}{125}$$