<human>:  Kara mixes cups of sugar and water in the ratio of 1:2 to make one liter of lemonade. Calculate the total number of cups of sugar used if she used 84 cups to make lemonade.
<bot>: How many cups of sugar and water are needed to make lemonade? ** The total ratio for the cups of sugar and water needed to make lemonade is 1+2 = <<1+2=3>>3
How many cups of sugar are needed to make one liter of lemonade? ** In the 3 cups needed to make one liter of lemonade, the fraction representing the cups of sugar needed is 1/3.
How many cups of sugar did Kara use? ** If she used 84 cups while making lemonade, she used 1/3*84 = <<84*1/3=28>>28 cups of sugar.
#### 28