The second matrix answer is found by Det(2nd matrix)/10, and the third matrix answer is found by Det(3rd matrix)/10. So if you just plug those numbers in on your graphing calculator in the matrix section, and find the determinant of the matrix, you should be able to enter the equation shown above. Once you get the answers to both of the matrices, just add them together for your final answer. Sorry if this seems cluttered, its the best I could do. Hope this helped.