to start off, if we look closely we will see that 37 + y = 180 because of the straight line that they form if added together. so, we can subtract 37 from both sides to get, y = 143. if you want to test it out with 3x + 1, you can simply find x by equaling this to 37 because they are each others’ vertex. so, 3x + 1 = 37 and simplified, x = 12.
