Thevenin's theorem application to find Vth

[gikwiye]

Homework Statement

question 3 part b ( see attachment)

Homework Equations

thevenin theorem

The Attempt at a Solution

the answer should be 10.98v for Vth (thevenin equivalent voltage)
all my attempts were unsuccessfull.
I found voltages such as 22.2 volts
i think I lake understanding of the thevenin's theorem because I cannot apply it when it comes to complex questions such as this one.

Thanks to anyone who helps.

 

[Red_CCF]

What method did you use to do your calculations, node voltage? Can you type them out?