The expression is
.
Write mixed fractions into improper fractions.
\
(
)
(
)
For every number
, where b, c, d 
(Multiply by the reciprocal of
is
)
(Product of two same signs is positive)
(If
)
(Cancel common terms)
(Multiply numerators:
)
(Multiply denominators:
)
The quotient of
is
.