Answer:
x=35
Explanation:
The line is a straight line which equals 180 degrees, so you form the equation 3x+75=180. You solve the equation by subtracting 75 on both sides, which gives you 3x=105, then divide 105 by 3 to get the value of x and you will get x=35.
3x+75=180
3x=180-75
3x=105
x=105/3
x=35