Question

What is the measure in degrees of <ABC?

Answer 1

Those two angles total equal 180 degrees. 
Since we know the first angle equals 155 degrees.
180-155+25.
ABC is 25 degrees. 

Answer 2

< CBD = 155
< CBD and < ABC are supplementary angles which, when added = 180

so...< CBD + < ABC = 180
           155 + < ABC = 180
           < ABC = 180 - 155
           < ABC = 25 <===