Angles DCA and ACB are supplementary angles therefore angles DCA+ACB=180 degrees which is 155+ACB=180 then subtract 155 on both sides and you get ACB= 25 degrees. Since all angles in a triangle sum up to 180 degrees therefore angles ACB+CAB+ABC=180 which is 25+115+ABC=180 then simplify 140+ABC=180 then subtract 180 on both sides and you get ABC=40 degrees! Which is B. Sorry I usually write it down and take a pic but since I’m on my bed I gotta type it out hope this helps