Solve the system of equations.
3x + 2y + 4z = 7
4x + 3y + 5z = 9
7x + 4y + 7z = 5
a (x = -5, y = 3,2 = 4)
b. (x = -6, y = 4, z = 5)
c. (x = -3, y = 1, z = 6)
d. (x = -4, y = 2, z = 3)