\[\boxed{\mathbf{200.}}\]
\[650 - 40 = 610\]
\[650 - 400 = 250\]
\[770 - 200 = 570\]
\[770 - 20 = 750\]
\[480 - 30 = 450\]
\[480 - 300 = 180\]
\[850 - 500 = 350\]
\[850 - 50 = 800\]