Having trouble figuring out angles when making piping

I know this is probably pretty easy for most but I am a beginner fabricator. I have recently got a job as a fabricator at a hot rod shop. My working interview was to build an exhaust for a LS swapped impala. From headers to over solid axle and making exhaust slash cut tips. I finished the job but figuring out how to make the pipes to the angles needed on 2.5 inch stainless steel mandrel bent piping ate my lunch. I struggled with knowing that I had Pipe A and Pipe C but getting the right angles for Pipe B is what I need help with. So my long winded question is what is the way to go about getting the angles and how do you cut the pipe accordingly to get it to fit correctly?

I've just measured with a digital angle ruler and then used a digital level on the bandsaw to get the right cut. Not an expert tough, just done a few systems.