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.

Quaternion.LookRotation

Quaternion.eulerAngles