I am reminded of a talk I attended in college about (elementary-level) math education. One of the first intro problems to estimation was something like 27+75, and the presenter showed us a (real) dialogue where the student gave the exact answer, and the teacher had to "correct" them to the estimate, and then proceeded to talk about how this wasn't exactly correct. The teacher's guiding the student through the "proper" reasoning was convoluted, and not effective teaching. The presenter concluded that if you teach estimation, you should use an example like 209385324579+394875293745, where estimation is actually faster and easier than exact arithmetic.
Now, what real-life example demands systems of equations? I suspect none, until you get into industrial applications. Therefore, maybe you should ask what the kid wants to be when he grows up, and create an example in that setting.
My wife painted our porch floor in sort of an argyle pattern with a border. That takes two equations and two variables to work out a pleasingly proportioned pattern that also meets the border in a uniform way.
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.
Now, what real-life example demands systems of equations? I suspect none, until you get into industrial applications. Therefore, maybe you should ask what the kid wants to be when he grows up, and create an example in that setting.