ignore these dumb *****. stay in college. it gets better. once you understand it, its quite easy.
To make things easier, take off the notation so you see actual numbers rather than scientific numbers so 4.6x10^3=4600kg/s
then just plug them in. I mean, it gives you the fricken variables lol.
only thing is, I wonder if your professor is a stickler. I mean, he could be a real *** and say that for you must also calculate in the changing weight of the rocket as it takes off. Not hard to do, just adds one more step lol.
Make sure you know how to take derivatives correctly though