Colston knows that his teacher loves drinking coffee and one day wants to see how much she drinks each week. He sees that she has a 20-ounce thermos and when she makes her coffee she pours a 1/2 cup of milk in, and then fills the coffee to the top. She does this twice a day. After the five-day school week, he decides to tell her, and when she hears how much coffee she drinks, she decides to drink 1/4 of what she normally drinks. How many ounces of coffee does she now drink a week?
1/2 a cup = 4 ounces.
Each thermos contains 16 ounces of coffee because 20 - 4 = 
<gadget id="calculator">20-4</gadget>
<output>16</output>
16.
She drinks 32 ounces a day because 2 x 16 = 
<gadget id="calculator">2*16</gadget>
<output>32</output>
32.
She drinks 160 ounces a week because 32 x 5 = 
<gadget id="calculator">32*5</gadget>
<output>160</output>
160.
She starts drinking only 40 ounces because 160 / 4 = 
<gadget id="calculator">160/4</gadget>
<output>40</output>
40.

<result>40</result>