Eh either one will work. The only difference between those two equations is that one produces a negative answer while the other one produces a positive answer. You get a positive answer if you choose upward to be the direction of the net force and negative if you choose the downward direction to be the net force. In the latter case, a negative answer simply means the net force is opposite of the chosen net force.
I think you have given the solution of example wrong as F must be equal to F=Fb-Fg but you have given F=Fg-Fb
Eh either one will work. The only difference between those two equations is that one produces a negative answer while the other one produces a positive answer. You get a positive answer if you choose upward to be the direction of the net force and negative if you choose the downward direction to be the net force. In the latter case, a negative answer simply means the net force is opposite of the chosen net force.
AK LECTURES Thank you sir for your explanation i got it.