Help with data science: confusion matrix?

I need to evaluate the performance of a classifier A. The test set provided has a total of 100 instances, 70 of which are labeled ‘+’ and 30 are labelled ‘-‘. To establish a base line from which to compare from, I need to build the theoretical confusion matrix that one would obtain if one were to use this test set... show more I need to evaluate the performance of a classifier A. The test set provided has a total of 100 instances, 70 of which are labeled ‘+’ and 30 are labelled ‘-‘.
To establish a base line from which to compare from, I need to build the theoretical confusion matrix that one would obtain if one were to use this test set on an unbiased (50/50) random classifier R. Can someone please explain how to do this and what my confusion matrix should look like?
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