Alice and Bob are a typical couple in Suburbville, Illinois — two cars, two kids, and they hate to walk if they can help it. But today is Parade Day in Suburbville and they are all going to march in the parade. The parade runs from the Library to the VFW post, both of which have ample parking, of course. But those two points are miles from each other and from Alice and Bob's home. In fact, no point of the route is within walking distance of home.
There's another complication. Their children, Charley and Diane, have to sit in booster seats when riding in the car, and must be with at least one parent at all times. Booster seats can be moved from one car to the other, but Alice and Bob have only two and nobody is willing to carry them in the parade.
So without asking any sort of favors from anyone else, or buying, renting or borrowing anything, how can Alice, Bob, Charley and Diane march in the parade without walking any significant extra distance?
Needless to say, getting a taxi or ride share service is not an option.
Early on parade day, Alice and Bob drive both cars to the VFW post (the endpoint of the parade), bringing the kids along, of course. They leave one car there with no booster seats and all go home to have breakfast. When parade time is near, they all drive to the Library (the assembly point) and dutifully march in the parade.
When they reach the end, one of them drives the cached car alone back to the Library and either takes the car seats from the other car, or just switches cars. Then it's back to the VFW post for the rest of the family, and back to the Library again for the other car, which one of the parents drives home.