use the rule of 3 simples
hope i understand it right that there is 1 integer and 1/4 cups of sugar or can being 11/4 cups too
1 integer 1/4 = 5/4
5/4 cups of sugar for 20 cookies
x -------------------- for 6 cookies
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x = 6*(5/4) / 20 = (30/4)/20 = 30/80 = 3/8 cups of sugar for 6 cookies
hope helped
