How to find voltage across the resistor?
I suspect the transformer is ideal, and it is where you may be stuck.  Current into a polarity dot on one side means current out of the dot on other side.  Their magnitude will be exactly per turns ratio.
So, draw an arrow going into left side dot and assign it a current variable. Then draw an arrow coming out of the other dot (or in to non-polarity dot side if easier) and assign it the same current variable, but scale it by \$1/2\$.  Also, assign a voltage variable to one side, scale it and assign with appropriate polarity on the other side as well. Then you can write KVL and KCL equations to solve.

Below I have assigned variables that should help you write the needed equations,