Applying force to an object of equal mass, finding required force?

[gerard.caleb]

Homework Statement

The homework question is:
"A large football player student (1.0 x 10^2 kg) applies a 6.0 x 10^2 N force to another equally burly student (1.0 x 10^2 kg) sitting on a sled (13.2 kg). If sliding friction and air resistance (drag) is 99.5 N, find the acceleration of the sled. In addition, how much force does the football player need to apply to the ground to accomplish this feat? Remember, he needs to get himself moving too!"

This is probably very easy but my teacher has been away for a week and we aren't supplied textbooks, and unfortunately the supply teachers we've had haven't been very proficient in physics.

Homework Equations

Not sure.

The Attempt at a Solution

The only thing we've done is very very basic stuff like calculating net force when already given the values, so I'm not really sure how to even approach this.

Can someone please explain how to go about this? I'm not really asking for you to solve it for me, because I'd like to learn how to go about these questions, but if you'd think it would help to treat this as a sample question then by all means!

Thank you!

*edit!

I think I know how to get acceleration, it's F=Fa-Ff=600-99.5=500.5N
so f=ma
a=f/m
a=500.5N/113.2kg
a=4.42 m/s^2

I'm hoping that's correct, anyway!

I'm still not sure how to find the force, though.

 

[haruspex]

I'm still not sure how to find the force, though.

Same eqn, F=ma, but now you want the acceleration from the first part, the net force on the first student and that student's mass.