There is no graph to support the statement and so, this invisible graph is misleading :)
Place the point of the compass on the intersection of AB and CD and extend the compasses to point R.
The ratio is 6w = 4f.
Multiply both sides by 3/2 to get 6 cups of flour, and we have:
6*3/2 w = 4 * 3/2 f
18/2 w = 12/2 f
9 w = 6 f
So 9 cups of water.
