as m abe = 2b, it seems like abe is the whole angle and abf and ebf are the parts of angle abe, then m abe = m abf + m ebf and we have to find m ebf so, m ebf = m abe - m abf now putting the values of angles abe and abf, we get m ebf = 2b - (7b -24) m ebf = 2b - 7b + 24 mebf = -5b + 24
