Answer :

Everything is right until the 3x +90=180

you want to subtract 90 to get:

3x=90

the divide by 3

x=30 

So the measure for angle t would be 60 degrees
AL2006

Your first two lines are beautiful.  That's exactly
the right way to approach this:

         2x + 90 + x  =  180

         3x + 90  =  180 .

But then I don't know what your third line means,
or even where it came from.

Here where you need to go after the first two lines:

  (second line) . . .                 3x + 90  =  180 .

Then, subtract 90 from each side:    3x  =  90

Divide each side by  3  :            x  =  30

Angle ' T '  =  2x   =   60 degrees. 

Angle ' V '  =  x   =   30 degrees.

Check:  60 + 90 + 30  =  180 degrees   yay !