Помогите пажалуиста даю 36 баллов

Решите задачу:

$\displaystyle \tt 1). \ \ \bigg(-6\frac{2}{3}\bigg)+(-8,75)+\bigg(-2\frac{5}{12}\bigg)=-\bigg(6\frac{8}{12}+8\frac{9}{12}+2\frac{5}{12}\bigg)=\\\\\\{} \ \ =-16\frac{22}{12}=-17 \frac{10}{12}=-17\frac{5}{6};\\\\\\2). \ \ \bigg(-3\frac{7}{15}\bigg)+(-0,4)+\bigg(-6\frac{1}{3}\bigg)=-\bigg(3\frac{14}{30}+\frac{12}{30}+6\frac{10}{30}\bigg)=\\\\\\{} \ \ \ =-9\frac{36}{30}=-10 \frac{6}{30}=-10,2;$

$\displaystyle \tt 3). \ \ (-1,5)+\bigg(-3\frac{4}{5}\bigg)+\bigg(-8\frac{3}{20}\bigg)=-(1,5+3,8+8,15)=-13,45;\\\\\\4). \ \ \bigg(-2\frac{5}{8}\bigg)+(-9,25)+\bigg(-\frac{3}{4}\bigg)=-(2,625+9,25+0,75)=-12,625;$