x
4
y
-
2
(x y
2
)
-
2
=
x
4
y
-
2
x
-
2
y
-
4
by rule (c)
=
x
4
-
(
-
2)
y
-
2
-
(
-
4)
by rule (b)
=
x
6
y
2
by rule (a)
