4. Сократи дроби. a) 17/51 = b) 11/55 = v) 7/28 = r) 18/30 =

а) $$ \frac{17}{51} = \frac{1}{3} $$

б) $$ \frac{11}{55} = \frac{1}{5} $$

в) $$ \frac{7}{28} = \frac{1}{4} $$

г) $$ \frac{18}{30} = \frac{3}{5} $$