For starters, when the tub drains, unless there is a vent for both the shower and the tub, that are separate, the p-trap on the shower is going to siphon dry when the tub drains.
Washington State UPC
You can run a 2" trap arm 60" before the vent
and for a 1.5" trap arm, 42" before the vent.
The revents need to be 42" above the floor.
In this case, the shower and the tub have vents that can be tied in together at 42" above the floor.