Show your work i don't know what to do it's hard

That's basic trigonometry
Tangent 57 degrees = AC / 9
AC = Tangent 57 degrees * 9
AC =  1.5399 * 9
AC = 13.8591 Rounding to one tenth =
13.9

You need to get x by itself. To do so you need to perform the opposite operations that are presented in the equation. Also, the operations furthest from the x should be done first.

In this case, there is only one operation (subtraction). To get x by itself we need to ADD 4 to both sides.

x = 11