Get the needed rotation to face other object

Hello i don't know how i can get the direction i need to turn to face a other object.

Situation : I got 2 objects, "A" am i and "B" is my target. I am rotated in a random way away from B.

Question: how do i get the needed rotation for "left and right" in degrees and "up and down"? so i get something like "your target is -160 to the left and 50 degrees up"

i know about transform.lookAt but i don't want unity to do that i just need to know the numbers for further scripting a autopilot.