Question

You need 1 1/4 cups of sugar to make 20 cookies to make 16 cookies you will need

Answer 1

1 1/4 =1.25

so 1.25 / 20 = 0.0625 each cookie needs this much sugar.

0.0625 x 16 = 1

16 cookies you will need 1 cup of sugar

Answer 2

First turn the fraction into an improper fraction 1 1/4 = 5/4

Set up a proportion:

$\frac{\frac{5}{4}\ cups}{20\ cookies} = \frac{x\ cups}{16\ cookies}$

Cross multiply you get

(5/4)*16 = 20x

20 = 20x

x = 1

So 1 cup of sugar