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?
Mrs. Fredrickson has 80 x 1/4 = 
<gadget id="calculator">80*1/4</gadget>
<output>20</output>
20 roosters.
So he has 80 - 20 = 
<gadget id="calculator">80-20</gadget>
<output>60</output>
60 hens.
Only 60 x 3/4 = 
<gadget id="calculator">60*3/4</gadget>
<output>45</output>
45 of the hens lay eggs.
Thus, 60 - 45 = 
<gadget id="calculator">60-45</gadget>
<output>15</output>
15 hens do not lay eggs.
Therefore, Mr. Fredrickson has a total of 15 hens + 20 roosters = 
<gadget id="calculator">15+20</gadget>
<output>35</output>
35 chickens that do not lay eggs.

<result>35</result>