Being able to brute-force mentally these kind of vans/cars problems is a useful skill in life, but it's not going to be learned by solving systems of equations.

Being able to brute-force mentally these kind of vans/cars problems is a useful skill in life, but it's not going to be learned by solving systems of equations. Actually, if you fudged the numbers a bit, you'd end up with equations that yield non-integer solutions, which you'd then have to play with in order to get an acceptable solution in real life.