[![enter image description here](https://i.stack.imgur.com/dzdEC.png)](https://i.stack.imgur.com/dzdEC.png)

The flux in the gas can be written as:

$$N\_{1}=k\_{p}(p\_{1}-p\_{1i})$$

And the flux in the liquid can be written as:
$$N\_{1}=k\_{x}(x\_{1i}-x\_{1})$$

And we know that $$x^\*\_{1}=\frac{p\_{1}}{H}$$

How can I use this to find the overall mass transfer coefficient?
I know that the driving force will just be $(p\_{1}-Hx\_{1})$ but what's $K\_{g}$ and more importantly, how is it derived?

EDIT: I'll give the best answer to anyone who can even give a hint