But anyways, think of it this way. The whole trip takes her X minutes, from Home to Friend's House. Let's call the distance between the Post Office and Friend's House \(Y\). To walk (2+Y) miles, it takes her X minutes.

If she can walk a mile in Z minutes, she can walk the distance from Home to Post Office in 2Z minutes. The time she takes to walk from Post Office to Friend's House is X - 2Z, which we will call A. To find the distance between PO and FH, we have (A minutes) * (1 mile / Z minutes). The minutes cancel out, giving us A miles / Z. Putting any values for A and Z will give us the answer for the distance from PO to FH.

Hope this helps,

- PM