Newtons first law

Part A
I learned about newtons first law which is "An abject at rest tends to stay at rest and an abject in motion tends to stay in motion with the same speed and in the direction unless acted upon by an unbalanced force." I also learned how to draw Free body diagrams,calculate different types of forces like normal force and frictional force and some others. I also learned about equilibrium which is if the vector sum of the forces acting on the object is equal to zero.
The difficult part about this is trying to find the equation that fits with the free body diagram and calculating the forces is a little confusing. And the best part that I do very well id drawing free body diagrams.

Part B
The only connection that i can really make with this is inertia. Another is finding the normal force of an abject at rest or the frictional force of an object sliding on the ground.