Answer:
x=45
Explanation:
Straight angles/lines are equal to 180 degrees. If you add the equations together to get 180 and simplify you'll find the answer. So, start out with the equation 2x+45+x=180.
1. Add like terms. 3x+45=180
2. Subtract 45 from both sides. 3x=135
3. Divide by 3 on both sides to get x by itself. x=45
4. Just to make sure, plug in 45 for x. 2(45)+45+45=180. Sure enough, it works!