The rate law for a first order reaction is:
rate = k x [A]
where k is the rate constant and [A] is the concentration of the reactant A. The rate of a first order reaction depends only on concentration of one reactant.
Here, rate = 0.060 M/s and [A] = 0.030 M.
From the first equation, we can write:
k = rate / [A]
k = 0.060 M/s / 0.030 M = 2 s^-1