Answer:
6x / (y - 6)
Step-by-step explanation:
y - 6 = (0 - 6/a - 0)(x - 0)
y - 6 = -6/a × x
y - 6 = -6x / a
1/a = (y - 6)/6x
a = 6x/(y - 6)
I hope this helps you :)