please solve all four parts of the question! thank you!

meant for advanced math sorry

Q1. For the system of linear equations below, 2x1 + 5x2 + 7 = 0 2x1 + x2 + x3 - 7 = 0 3x1 + x2 - 9 = 0 (1). Write down the equations in matrix form: Ax= b. (ii). Find the determinant of the coefficient matrix, A? (iii). Solve the equations using Cramer's rule