hi kise,
Welcome to AAC.
As this is Homework please post you attempt at solving the problem, we can then help you.
E

 

how can i post that

 

hi,
Usually the student types in the required equations or which method they plan to use in solving.
Or
you could use pencil and paper, take a photo shot and post an image of the work.
E

 

if you redraw your uploaded figure (more top-down for grid's voltage gradient) using the 2kΩ .. ?? .. as internal resistance of your supply the Vth becomes obvious (assuming RTH is just one possible adjusted RL value)