Answer:
D. $81.
Explanation:
We know that,
Contribution margin per unit = Selling price per unit - Variable expense per unit
For Q-Drive, it would be
= $210 - $150
= $60
For Q-Drive Plus, it would be
= $270 - $180
= $90
Now the weighted contribution margin would be
= Q-Drive contribution margin × sales mix + Q-Drive Plus contribution margin × sales mix
= $60 × 30% + $90 × 70%
= $18 + $63
= $81