Answer:
40 Bran Muffins
80 Blueberry Muffins
Explanation:
Let the number of Bran muffins ordered = x 
The number of Blueberry muffins ordered = 2x <em>(it is given that the number of blueberry muffins is twice the number of bran muffins)</em>
<em />
The cost of Bran muffins ordered = Number of Bran muffins * cost of 1 muffin
Cost of Bran muffins ordered = x * 2 
Cost of Bran Muffins ordered = $ 2x
The cost of Blueberry muffins ordered = Number of Blueberry muffins * Cost  of 1 blueberry muffin
Cost of Blueberry muffins ordered = 2x * 4 
Cost of Blueberry muffins ordered = $ 8x 
Since the sum of costs of Blueberry and Bran muffins is $400
Cost of Bran muffins + Cost of Blueberry muffins ordered = 400
2x + 8x = 400
10x = 400
x  = 40 
Hence, the number of Bran muffins ordered is 40 
we are told that the number of Blueberry muffins is twice the number of Bran muffins 
So, 
Blueberry muffins  = Bran muffins * 2
Blueberry Muffins = 40 * 2 
Blueberry muffins = 80
So, the number of Blueberry muffins is 80