2. Horizontal Surface (no friction)
FN= mg (Remember FW= mg)
This means it is equal in magnitude NOT in direction FN FW

3. On an Incline (no mu, - no friction)
So, FN is perpendicular to the SURFACE of the contact force. FN FN FN
Horizontal surface FP F F FP
Any force at an angle to a horizontal surface is resolved from FW into two components. 1 parallel to the incline surface (FP)
And the other perpendicular to the incline surface (F ). F is opposite FN so FN= FP is not balanced resulting in acceleration.
FP=FNET. F F F

4. On an incline place with friction
balances FN; you must also consider FF. FNET is
the vector sum of all the forces.
= 43 N FF
=20 N
FNET= (FN FP +- FF) F
FNET = = 5 N directed along the incline
towards the floor.
Remember FP = FNET
= 25 N
=43 N