Answer :
we know angles A and B are supplementary, thus their sum is 180°.
[tex]\stackrel{\measuredangle A}{(2x+26)}~~ + ~~\stackrel{\measuredangle B}{(x+25)}~~ = ~~180\implies 3x+51=180\implies 3x=129\\\\\\x=\cfrac{129}{3}\implies x=43~\hspace{10em}\stackrel{\measuredangle B = 43 + 25}{68}[/tex]