Question

The ratio of white flour to whole wheat flour in a bread recipe is 2:3. The recipe uses 60 cups of flour. How much white flour is needed

Answer 1

So white flour to whole wheat is 2:3, and wheat flour is 60 cups.

Lets put it this way, 2 white flour = 3 wheat flour
If we have 60 cups of wheat flour, we are multiplying the above equation by 20 to get 3 x 20 - 60 cups of wheat flour.

2 white flour = 3 wheat flour (times 20 is 60, which is what they're asking)

Now we need to multiply 20 on both sides, because what you do on one side must be done to the other.

2 white flour = 3 wheat flour
x 20                    x 20

40 white flour = 60 wheat flour

The final answer should be 40 cups of white flour is needed when the recipe uses 60 cups of wheat flour.
 
Hope this helps! :)

Answer 2

40 cups of white flour if you set it up as a fraction and cross multiply with x