Giving directions on the phone

— Hi Selma. I'm on 40th Street, but I can't find the post office. I went past State Street; didn't you say it would be on the left-hand side?
— Yes, it should be, next to the grocery store. Are you sure you're on Northeast 40th?
— Oh no, I'm on Northwest 40th. What should I do?
— OK, turn around and follow 40th back to State Street. Go under the freeway overpass to the intersection. You'll see a gas station on the right. Go straight, and 40th will change from northwest to northeast. Now the post office will be on your right, next to the DVD store.