Answer:
First, you know that a triangle has 180° total. So, you take 180-38-25 and that equals 117. So the corner inside the triangle is 117. So a straight line is also equal to 180. You take 180-117 and that is 63. 4x+3 = 63. You subtract 3 from both sides and get 4x = 60. To get x by itself you divide by 4 and x = 15.
