The question is reproduced in the table below for clarity 
 Oven Contribution
 Hours Required Margin Per Unit
Muffins 0.2 $4
Coffee Cakes 0.3 $5
Answer:
 Total contribution margin = $ 60,000.00 
Step-by-step explanation:
When a business is faced with a problem of shortage of a resource which can be used to produced more than one product type, to maximize the use of the resource , the business should allocate it for production purpose in such a way that it maximizes the contribution per unit of the scare resource.
Therefore Crane Company should alocate the oven hours to maximise the contribution per unit of oven hour. This is done as follows:
Step 1 
Calculate he contribution per oven hour and rank the product
 cont/hr ranking
Muffin $4/0.2 hour = 20  1st
Coffee cakes $5/0.3 hour= 16.67 2nd
Because Muffin generates the highest contribution per hour of Oven, Crane should allocate all the resource to it
Step 2 
Calculate the Total contribution from the production of Muffin
Total contribution margin = 20 per her × 3000
  = $ 60,000.00