Помогите решить эти два примера

$1) \\ ( \frac{4}{5} - \frac{3}{4} ) \times ( \frac{3}{4} - \frac{4}{5} ) = \\ ( \frac{4 \times 4 - 3 \times 5}{20} ) \times ( \frac{3 \times 5 - 4 \times 4}{20} ) = \\ ( \frac{16 - 15}{20} ) \times ( \frac{15 - 16}{20} ) = \\ \frac{1}{20} \times ( - \frac{1}{20} ) = - \frac{1}{400}$

2) 8 13/20 - 18 103/120+ 10 5/24= 173/120 - 2263/120 + 10 5/24= -1225/120 + 10 5/24= -10 5/24 + 10 5/24=0