Help with this chemistry question firs order rate law..

Question

I need to figure out the steps to solve this first order rate law problem but I am having a hard time rearranging. Can someone please show me the steps?

 

Question --

 

The first-order decomposition of cyclopropane has a rate constant of 6.7 x 10-4 s-1. If the initial
concentration of cyclopropane is 1.33 M, what is the concentration of cyclopropane after 644 s?

Answer 1

First order rate equation:  ln[A] = -kt + ln[A_O]

                             ln[cyclopr.] = -6.7*10^-4 (644) +  ln 1.33 

                                              = -0.1463

                            [cyclopr.]    = e^-0.1463 = 0.864 M