Ответ:

1)6

2)-19/44

3)-10/21

4)9/35

Пошаговое объяснение:

1) ...=(-1)*(-1)*(4*9*25)/(15*10)=

=(2*2*3*3*5*5)/(3*5*2*5)=

=2*3=6

2)...=36/44-(19/44 + 36/44)=36/44-19/44-36/44=

=-19/44

3)...=-27/42-(5/42-2/7)=-27/42-5/42+12/42=

=(-27-5+12)/42=-20/42=-10/21

4)...=-1/4*(-8/5+4/7)=

=-1/4*(-56/35+20/35)=(-1/4)*(-36/35)=

=(-1)*(-1)*(1*36)/(35*4)=

=(4*9)/(35*4)=9/35