а) 3a + 3b + c(a+b)
3(a+b) + c(a+b)
(3+c)(a+b)

б) 2(m+n) + km + km
2(m+n) + 2km
2(m+n+km)

в) by + 4(x+y) + bx
by + bx + 4x + 4y
b(y+x) + 4(x+y)
(b+4)(x+y)

г) a(x-y) + bx - by
a(x-y) - by + bx
a(x-y) + b(x-y)
(a+b)(x-y)

д) 3b - 3c + a(b-c)
3b - 3c + ab - ac
3(b-c) + a(b-c)
(3+a)(b-c)

е) ab + 2(b-d) - ad
ab + 2b - 2d - ad
ab + b - 2d - ad
b(a+1) - 2(d+a)