Ellie is making a batch of pancakes and her recipe calls for 1 1/2 cups of flour and 1 1/4 cups of milk. If she only has 1 cup of milk, how much flour should she use to make the same pancake recipe?

Answer 1

Let's set this up like a ratio problem:

^{1.5 flour} / _{1.25 milk} = ^x / _{1 milk}

^{1.5 flour * 1 milk} / _{1.25 milk} = x

Anything times one is itself. The milks in the numerator and denominator cancel out:

^{1.5 flour} / _1.25 = x

--------

1.25|1.5

Dividing by a decimal means moving the decimal place over for both numbers:

1.2

------------

125|150.0

-125

------------

250

-250

--------

0

So Ellie needs 1.2 or 1 1/5 cups of flour (as ²/₁₀ simplifies to ¹/₅).