252 задание! срочно!

Решите задачу:

$1) \frac{12*5+12*9}{12*21} = \frac{12*(5+9)}{12*21} = \frac{14}{21} = \frac{2}{3} \\ \\ 2) \frac{8*8-8*7}{8*5} = \frac{8*(8-7)}{8*5} = \frac{8*1}{8*5} = \frac{1}{5} \\ \\ 3) \frac{14*5-14*2}{28} = \frac{14*(5-2)}{28} = \frac{14*3}{28} = \frac{3}{2} =1 \frac{1}{2} \\ \\ 4) \frac{19*8-19*6}{38} = \frac{19*(8-6)}{38} = \frac{19*2}{38} = \frac{38}{38} =1$