(х-у)+(2у-3b)=х-у+2у-3b=
=y+x-3b
-(a-b)+(-x+a)-(b-x)=
= -a+b-x+a-b+x=0
-(x-9)+(a-5)= -x+9+a-5=
=a-x+4
(a-7)-(5+a)-(9-a)=
=a-7-5-a-9+a=a-21
(x-a)+(y+b)= x-a+y+b
-(m+n)+(n-p)-(-p-m)=
= -m-n+n-p+p+m=0
(b-4)-(-c+7)=b-4+c-7=b+c-11
(-m+8)-(m-4)+(-8+m)=
= -m+8-m+4-8+m=
=4-m
-2(x-y+z)= -2x+2y-2z
3(-a+b)= -3a+3b
-2(2x-5y)= -4x+10y
0,3(-30a+40b)= -9a+12b
-2(-a+b+c)=2a-2b-2c
4(-m-n)= -4m-4n
-3(-2a+5b)= 6a-15b
0,5(20c-60d)=10c-30d
2(a-9)-3=2a-18-3=2a-21
-3(x+2)+10= -3x-6+10=4-3x
5(4-x)-(-5x+1)=
=20-5x+5x-1=19