A triangle all adds up to 180°.
Therefore you must add them all up and equal them to 180.
Shown below:
2x+1+3x+x+5=180
Then of course you have to solve it.
Shown below:
6x+6=180
Move the 6 over to the side of 180 which leaves 6x by itself.
Shown below:
6x=180-6
Then solve the equation:
6x=174
Solve x:
x= 174/6
Hence, leaving x as 29°
After finding x, you must substitute it in the x values. Hope this was helpful.