Do you only look at the first numbers like 2x and 5x because the other numbers are so small they are not significant. I know the answer is 0,0 for the first one and 7,7 for the second one.

Is this because 7(infinity)^3 / 1(infinity)^3 is rougly going to be 7... and the other numbers don't even come into play? Or am I thinking about this completely wrong?