While I normally just teach math, this summer I am also tutoring. I am enjoying the tutoring because it allows me to assist students with different mathematical topics than I normally do not get to teach. One of the popular subjects in the tutoring center this summer in finite math. Finite math is not a particular topic in math but rather a broad category that covers a variety of topics.
The topic of Matrices seems to generate a lot of questions. I found several helps this summer dealing with matrices and in particular the Simplex Method.
The first site I found was How to Compute Determinants at Dartmouth College.
The second site I found was Finite Mathematics & Applied Calculus Resource Page. It has two very good lessons on the Simplex Method.
The last site I found is not really a site but rather a YouTube channel by patrickJMT.
Here is a list of some of his videos dealing with matrices.