The answer says the voltage is 8.772 V and the resistance is 210.53 Ohms:

I got the right value for voltage. I can't figure out where the resistance comes from.

For resistance, I calculated the total resistance with 300 and 1k in parallel, that resistance in series with 400, and that resistance in parallel with 2k. And what I get is:

\[ \frac{(\frac{1000*300}{1000+300}+400)*2000}{(\frac{1000*300}{1000+300}+400)+2000}\approx479.532 \]

I even simulated the circuit on an app to see if I made a math mistake, and that's the resistance I get between the two rightmost nodes. I'm inclined to think it's a mistake in the worksheet, but maybe I just don't understand Thevenin's Theorem.