Answer:
plain makes a profit of $10 
Step-by-step explanation:
The computation is shown below:
Particulars Plain fancy
Unit contribution margin $58 $57
Machine hours 2 3
Contribution margin 
per machine hour $29 $19
 ($58 ÷ 2) ($57 ÷3)
As we can see that the plain makes a profit of $10 that comes from 
= $29 - $19
= $10