Даю 20б. Задача №7 (1,2).

1) $( \frac49+(- \frac56)):(- \frac{14}{27})=-( \frac49- \frac56): \frac{14}{27}=-( \frac{8}{18}- \frac{15}{18}): \frac{14}{27}=-(- \frac{7}{18}): \frac{14}{27}=$ $\frac{7}{18}: \frac{14}{27}= \frac{7}{18}* \frac{27}{14}= \frac{27}{18}* \frac{7}{14}= \frac{3}{2}* \frac12= \frac34=0,75.$ 2)(-1.5*4)-2=-6-2=-8 3)(-1,9-0,9)(-1,9+0,9)=-2,8*(-1)=2,8. 4)(6-8)³=(-2)³=-8.