Phy que 18.

Let a=30.0cm, b=20.0cm, and c=10.0cm. From the given hint, we write

mu
=
?
1
?

?
+
?
2
?

?


=iab(?
k
^
)+iac(
j
^
?
)

=ia(c
j
^
?
?b
k
^
)

=(5.00A)[(0.100m)
j
^
?
?(0.200m)
k
^
]

=(0.150
j
^
?
?0.300
k
^
)A?m
2
.