Say you have 3 cakes. How many cakes would you have eaten if you ate 1/3 of the three cakes? One, you have eaten one cake, out of the three you have.
How many cakes do you have left if you eat 2/3 of the three cakes? Two, you have eaten 2 cakes, and have 1 cake left.
It is a similar approach here, except the confusing part is working "forward", when you really have to work "backward". If you have driven 30 miles, and you have driven 2 parts out of the trip when there is 3 parts of the trip, how many miles have you driven? Hint: Dividing 30 by 2 gives you what fraction of the distance to Jeff's grandmother?
