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 = <<20-4=16>>16
She drinks 32 ounces a day because 2 x 16 = <<2*16=32>>32
She drinks 160 ounces a week because 32 x 5 = <<32*5=160>>160
She starts drinking only 40 ounces because 160 / 4 = <<160/4=40>>40
#### 40