Solve for x.
Need help, Thank you!!
Also, i need explanation.

Answer:
7.) x = 12
9.) x = 4
Step-by-step explanation:
7.) Angle Y and Angle X both add up to 180
=> 40 + 12x - 4 = 180
=> 36 + 12x = 180
=> 12x = 180 - 36
=> 12x = 144
=> x = 12
9.) Angle W and Angle X add up to 180
=> 145 + (-1) + 9x = 180
=> 144 + 9x = 180
=> 9x = 180 - 144
=> 9x = 36
=> x = 36 / 9
=> x = 4
Hope this helps!