\[\boxed{\mathbf{180.}}\]
\[500 - 100 = 400\]
\[600 - 200 = 400\]
\[425 - 25 = 400\]
\[407 - 7 = 400\]
\[100 + 300 = 400\]
\[1000 - 600 = 400\]
\[700 - 300 = 400\]
\[430 - 30 = 400\]