Answer:
z = 6
9 followed by a lowercase number, whether it's x, y, or z usually always means add 1 or multiply by an unknown number. In this case, we are multiplying.
[tex]9 * 45 = 405(wrong)\\\\9 * 63 = 567(wrong)\\\\9 * 7 = 63(wrong)\\\\9 * 6 = 54(correct)[/tex]
That said, the answer is six.
