Ok, so you need force, wich is Force = mass * acceleration.

Now on your first question. acceleration is = velocity/time right? So in the initial formula instead of giving the formula the acceleration, you give it the velocity/time.

Force = (mass)(velocity/time)

Know the other problem is more complex, but you should follow a similar path. So

the momentum = mass * velocity

and we are asked to rearrange the newtons second law including the momentum.

Ill rewrite the newton second law

F = m * a

and momentum

p = m * v

 So now if you where to find the force using momentum first step will look like

1. F = p and some operation to determine

2. F = m * v and some other operation

As you looked so far we are kind of there but as you know velocity and acceleration is not the same.

Know if you remember acceleration = Velocity / Time

So there you, if we want the Force in therms of momentum the result will be

3. F = (m*v)/a

If you still have doubts or something isnt quite clear just hit me with a reply.

And more important than nothing, keep the good work!

If something you could do to exponentially be better at physics at this stage is learn how to clear equations (algebra) so learn pretty good fractions and exponents, and then master how to use units! Then is just pretty easy to do any exercise if you have a formula.

I get it now. Its telling me to rewrite it in another way that is similar to the equation as certain letters equal a certain equation.  But they are all the same. Thanks