I have an annoying Physics question that I have been trying to work at for about 3 hours now, the class I'm taking is Calculus based but I'm not even sure if this question is necessarily calculus-related, I'm not sure how I should be approaching it.

Here is a link because of the subscripts and notation not being transferrable...

I've tried graphing these functions, but I'm pretty sure I'm not doing it correctly or I don't know how to analyze it, especially with an extra 't' factor. I also tried to relate all of it in terms of the Earth, and then in terms of Mars, but nothing seems to be resulting in progress.

I also tried subtracting the x's and y's to get a resultant, doing a dot product by multiplying the x's and y's, and both times I just ended up at a halt.