Answer: b=11
Step-by-step explanation: If you try out all of the possible values, right away you get the first answer. Substitute 11 for be and you get 3(11)+1 which is 33+1 which is 34. Then do 114+32+34 which is equal to 180 degrees and all of the angles of a triangle have to be equal to 180 degrees. Hope this helps.