Idon’t know how to solve things like this

To do this problem you need to find angle adc which is a part of angle BDA. angle BDA is 90 degrees so the 2 parts must add up to 90 degrees so you set up the problem like this
-2x + 144 - 3x +51 =90
then you combine like terms
-5x +195 = 90
then you subtract 195 from 90
-5x = -105
then you divide -5 by -5 and -105 by -5 and get
x=21
then you plug x in and get your angle measure
-3(21) +51
then you get the angle measure as 114 degrees.

I’m not sure what it is i sorry : ((