Сократите: а)6×13/26×12; б)24×14/49×36; в)3×4×5/6×12×50; г)9×20-9×7/9×23+9×3

Решите задачу:

$\frac{6 \times 13}{26 \times 12} = \frac{1}{2 \times 2} = \frac{1}{4}$
$\frac{24 \times 14}{49 \times 36} = \frac{4}{7 \times 3} = \frac{4}{21}$
$\frac{3 \times 4 \times 5}{6 \times 12 \times 50} = \frac{1}{2 \times 3 \times 10} = \frac{1}{60}$
$\frac{9 \times 20 - 9 \times 7}{9 \times 23 + 9 \times 3} = \frac{20 - 7}{23 + 3} = \frac{13}{26} = \frac{1}{2}$