First, I realized that ∠S was equal to ∠T, meaning ∠S=2x+2. I then added all 3 angles together and set them equal to 180, seeing the angles of a triangle must add up to 180 (2x+2+2x+2+3x+1=7x+5=180)
After that, I subtracted 5 from 180 and then divided by 7 to get x=25. I then solved the equation 3x+1 by plugging 25 in for x and ended up with 76 as my final answer.