$[10$pts$]$ Using the confusion matrix below, please calculate $($a$)$ accuracy of the model and $($b$)$ precision for class A and $B.$

Hint: Class A $($or B$)$ is the positive class when the precision for class A $($or B$)$ is computed.

$\backslash$table$[[,$Predict$],[,$A$,$B$],[,$A$,450,150],[$B$,100,350]]$