5/6-2/3*7/8-1/2*-4 Пожалуйсто помогите

Решите задачу:

$(\frac{5}{6} - \frac{2}{3}) *( \frac{7}{8} - \frac{1}{2} )*(-4) =-0,25$

$1) \frac{5}{6} - \frac{2}{3} = \frac{1*5-2*2}{6} = \frac{5-4}{6} = \frac{1}{6}$

$2) \frac{7}{8} -\frac{1}{2} = \frac{1*7-4*1}{8} = \frac{7-4}{8} = \frac{3}{8}$

$3) \frac{1}{6} * \frac{3}{8} = \frac{1}{2} * \frac{1}{8} = \frac{1}{16}$

$4) \frac{1}{16} *(-4)= - \frac{1}{16} * \frac{4}{1} =- \frac{1}{4}* \frac{1}{1} =- \frac{1}{4} = -0,25$