Okay so (5x+5)+115 is going to equal 180.
1.) (5x+5)+115=180
The next steps is to isolate the x.
2.) 5x+120=180
3.) -120=-120
4.) 5x=60
5.) /5=/5
6.) x=12 degrees
Then, you check your work by plugging in the numbers.
7.) 5(12)+5+115=180
8.) 60+5+115=180
9.)180=180