drain pipe

Can a 3" double fixture tee be used in place of a 3" 45 drain double wye and 1/8th bend? The bottom of the barrel sweeps into the cesspool drain line. On top is the toilet san-tee and above the vent stack. One side is the drain for the shower (with vent immediately downstream of intersecting...

hi guys, I'm new here and by no means a professional ... Trying to plum this new sink I have that sits lower then my old one.... Wondering if I can make this work (see picture) or if I will have to higher the sink OR lower the drain pipe?