If 1/4 of the 80 chickens are roosters, then there are 80/4 = 20 roosters.
The rest of the chickens are hens, so there are 80 - 20 = 60 hens.
If only three-fourths of the hens lay eggs, then 3/4 * 60 = 45 hens lay eggs.
Therefore, there are 60 - 45 = 15 hens that do not lay eggs.
In addition to the roosters, there are 15 hens that do not lay eggs, so Mr. Fredrickson has a total of 20 + 15 = 35 chickens that do not lay eggs.
#### 35
The answer is: 35
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Mrs.  Fredrickson has 80 chickens where 1/4 are roosters and the rest are hens. Only three-fourths of those hens lay eggs. How many chickens does Mr. Fredrickson have that do not lay eggs?

### Answer:
