Given matrix cap y is equal to the 2 by 2 matrix, row 1, column 1, 4 column 2, 8 row 2, column 1, negative 3 column 2, negative 6 and matrix cap z is equal to the 2 by 2 matrix, row 1, column 1, negative 1 column 2, negative 2 row 2, column 1, 7 column 2, 2 What is matrix cap x if 1 half times open paren cap x plus cap z close paren is equal to cap y ?