The answer is 71 degrees, considering that one is a right angle we know that it is 90 degrees and because all of the angles of a triangle added up is 180 we can do 180 - (90 + 42) = 48, 48 is a, then we know that angle B is on a supplementary angle with a so it would be 90 - a = b, plug it in it would be 90 - 48 = 42 then we would do the same thing to find angle c, 180 - (42 + 67) which equals 71
