Solve for kkk such that the system x+2y+z=4x + 2y + z = 4x+2y+z=4, 3x+8y+7z=203x + 8y + 7z = 203x+8y+7z=20, 2x+7y+kz=152x + 7y + kz = 152x+7y+kz=15 has infinitely many solutions.
k=5k = 5k=5
k=6k = 6k=6
k=7k = 7k=7
k=8k = 8k=8