Answer:
Madeline has spent a total of $318.67 + (2 * $12.89) + $30.57 = $366.04 on her new bike, reflectors, and gloves.
The amount of money Madeline has left to spend on biking outfits is $680 - $366.04 = $313.96.
We can write an inequality to determine the number of outfits Madeline can purchase while staying within her budget as follows:
$313.96 / $78.20 ≥ x
Solving this inequality gives us x ≥ 4, so Madeline can purchase at least 4 biking outfits while staying within her budget.