tolong yang jago matematika nomer 1 dan nomer 2

1)
18a^2 + 12a^3
---------------------
............6a

= 18a^2/6a + 12a^3/6a
= 3a + 2a^2

2)
xy - zx
-----------
....2x

= xy/2x - zx/2x
= y/2 - z/2
= (y - z)/2
= 1/2 (y - z)