ANSWER:
10
STEP-BY-STEP EXPLANATION:
We can calculate the value of x, knowing that the subtraction between the plane angle (180°) and 7x -10 is equal to 120°, therefore, we have the following equation:
[tex]\begin{gathered} 180-\mleft(7x-10\mright)=120 \\ \text{ Solving for x} \\ 180-7x+10=120 \\ -7x=120-190 \\ x=\frac{-70}{-7} \\ x=10 \end{gathered}[/tex]
The value of x is 10
