Second order reaction This is an example in my textbook that I am trying to figure out 

$1/[\ce{A}] = 1/[\ce{A}]_0 + kt$

In this case:
$[\ce{A}] = 4.62\times10^{-2}\ \mathrm M$
$[\ce{A}]_0 = 0.217\ \mathrm M$
$k = 0.540\ \mathrm{M^{-1}\ s^{-1}}$

so I get this
$1/(4.62\times10^{-2}\ \mathrm M) = 1/(0.217\ \mathrm M) + (0.540\ \mathrm{M^{-1}\ s^{-1}})(t)$

the answer should be 31.5 seconds

I can’t get this answer I must be missing something
in the order that it should be.
When you manipulate the equation to solve for t you'll want to subtract 1/[A]0 from 1/[A] and then divide by k.