21/98 20/84 ,15/27 28/48 15/54 28/48 к наименьшему общему знаменателю СРОЧНО НАДО

1)
$\frac{21}{98} = \frac{3}{14} = \frac{3*3}{14*3} = \frac{9}{42}$
$\frac{20}{84}= \frac{5}{21} = \frac{5*2}{21*2} = \frac{10}{42}$
2)
$\frac{15}{27} =\frac{5}{9} = \frac{5*4}{9*4} = \frac{20}{36}$
$\frac{28}{48} = \frac{7}{12} = \frac{7*3}{12*3}= \frac{21}{36}$
$\frac{15}{54} = \frac{5}{18}= \frac{5*2}{18*2} =\frac{10}{36}$
$\frac{28}{48} = \frac{7}{12} = \frac{7*3}{12*3}= \frac{21}{36}$