Answer:
12) x= 29 ; (4+5x) = 149° ; (x+2) = 31°
15) x=29 ; (2x+1) = 59° ; (x+2) = 31°
16) x=17 ; (4+2x) = 38° ; (3x+1) = 52°
Explanation:
So for each problem you follow the same steps.
1) See what the angles should measure up to. (#12 is 180°, and #15 & 16 is 90°
2) Write your equation. (I'm going to use #12 as an example). 4+5x+x+2=180
3) Simplify the equation. 6x+6=180
4) Solve the equation. x=29
5) Then replace each x with the 29, and solve.
6) To double-check the angles, add both angles together and they should be 180° (or whatever you decided you were solving for on step 1)