Here’s an easy tip. Always know that the angles next to each other, for example,AB, DC, AD& BC always equal to 180 degrees when added together. So, we know that angle A plus angle B is 180. Lets set it up. 2x+1+148=180 Combine like terms. 2x+ 149= 180 Subtract 149 from each side. 2x= 31 X= 15.5 degrees