a1 = 54
a2 = (1/3)a1 = (1/3) * 54 = 18
a3 = (1/3)a2 = (1/3) * (1/3)a1 = 18/3 = 6
etc.
[tex] y = 54(\dfrac{1}{3})^{x - 1} [/tex]
