а) x(y-z)-y+z = x(y-z)-(y-z)=(y-z) (x-1)
б) 2b(x-y)+y-x =2b(x-y)-(x-y)=(x-y) (2b-1)
в) 5(с-b)+ab-ac =5(с-b)-a(c-b)=(c-b) (5-a)
г) 2(x-c)-bx+bc =2(x-c)-b(x-c)=(x-c) (2-b)
