First, write the number of cups of sugar as an improper fraction:
[tex]1\frac{1}{4}=1+\frac{1}{4}=\frac{4}{4}+\frac{1}{4}=\frac{5}{4}[/tex]Divide the number of cups of sugar by the total number of cookies to know how much sugar is needed to make one cookie:
[tex](\frac{5}{4})\div20=\frac{5}{4}\cdot\frac{1}{20}=\frac{5}{4\cdot20}=\frac{5}{4\cdot4\cdot5}=\frac{1}{4\cdot4}=\frac{1}{16}[/tex]Multiply the number of cups of sugar that each cookie needs (1/16) times the number of cookies that you want to make (16):
[tex]\frac{1}{16}\cdot16=1[/tex]Therefore, to make 16 cookies, you need 1 cup of sugar.
