643.2:( -87,3+85,7)=402
1) -87,3+85,7 = -1,6
2) 643,2:( -1,6)= - 402
1 5/12 :(-5/6+2/3)= - 8 1/2
1) -5/6+2/3= - 5/6+4/6= - 1/6
2) 1 5/12 : ( -1/6)= - 17/12 * 6= - 17/2= - 8 1/2
p+( -m+r-p)=p-m+r-p=r-m
m-(a+m)-(-a-m)=m-a-m+a+m=m
6c*(-7)= - 42c
-5a*6b*(0/3 c)=0