ПОМОГИТЕ ПО МАТЕМАТИКЕ

Решите задачу:

$a)1 \frac{3}{4} \times 2 \frac{2}{5} \times \frac{5}{21} = \frac{7}{4} \times \frac{12}{5} \times \frac{5}{21} = \frac{7 \times 12 \times 5}{4 \times 5 \times 21} = \frac{1 \times 3 \times 1}{1 \times 1 \times 3} = \frac{3}{3} = 1$

$b) \frac{7}{9} \times 2 \frac{5}{14} \times 1 \frac{4}{5} = \frac{7}{9} \times \frac{33}{14} \times \frac{9}{5} = \frac{7 \times 33 \times 9}{9 \times 14 \times 5} = \frac{1 \times 33 \times 1}{1 \times 2 \times 5} = \frac{33}{10} = 3 \frac{3}{10} = 3.3$