If the flour to sugar ratio is 5 cups flour to 1 cup sugar, then how much sugar is needed if only 2 cups of flour are used?

##2/5## cups are needed.

You write it out as a ratio. ##(5/1)=(2/x)## You cross-multiply. ##5x=2*1## Simplify. ##5x=2## Divide each side by five to find the value of x. ##x=2/5## ##2/5## or ##0.4## cups of flour are needed.