Answer:
c
Step-by-step explanation:
7x+(13x-3)+(8x+15)=180
7x+13x-3+8x+15=180
28x+12=180
28x=180-12
28x=168
x=6
The answer is 6.
To check:
7(6)
42 degrees
13x-3
13(6)-3
78-3
75
75 degrees
8x+15
8(6)+15
48+15
63
63 degrees.
42+75+63=180
Therefore, x=6
