CPM Homework Help : PC Problem 6-111

Rewrite each trig expression in a simpler form using trigonometric identities.

$\operatorname { sin } ( \frac { \pi } { 6 } ) \operatorname { cos } ( \frac { \pi } { 4 } ) - \operatorname { cos } ( \frac { \pi } { 6 } ) \operatorname { sin } ( \frac { \pi } { 4 } )$
Hint (b):
$\sin(\text{A})\cos(\text{B}) − \cos(\text{A})\sin(\text{B}) = \sin(\text{A} − \text{B})$