$\"\"$

The expression is $\"\"$ .

For every number $\"\"$ , where b, c, d $\"\"$

$\"\"$ (Multiply by the reciprocal of $\"\"$ is $\"\"$ )

$\"\"$ (Product of two different signs is negative)

$\"\"$ (If $\"\"$ )

$\"\"$ (Multiply numerators: $\"\"$ )

$\"\"$ (Multiply denominators: $\"\"$ ) $\"\"$

The quotient of $\"\"$ is $\"\"$ .