$$\frac{1}{5} = \frac{1*6}{5*6} = \frac{6}{30}$$
$$\frac{4}{8} = \frac{4*6}{8*6} = \frac{24}{48}$$
$$\frac{7}{15} = \frac{7*6}{15*6} = \frac{42}{90}$$
$$\frac{13}{10} = \frac{13*6}{10*6} = \frac{78}{60}$$
$$\frac{37}{40} = \frac{37*6}{40*6} = \frac{222}{240}$$