Thread Subject: Power losses

good morning every body
Actually i have two questions and i'm looking for your help , my questions are :

1- if you want to calculate the active power losses between sending and reciving end in transmission line system L- M , is this equation ( Ploss = Psending + Preceiving ) correct or what is the correct equations ?

2- what is (the acceptable value) or the maximum value of the power losses in the transmission line system, specially the active power losses between the sending end and receiving end ?

3- any recommended references for Active Power losses