Using the Isolation method, we are to determine the rate law of the equation, RCOOR' + OH− → RCOO− + R'OH (where R and R' represent organic groups).

Question

Using the Isolation method, we are to determine the rate law of the equation, RCOOR' + OH− → RCOO− + R'OH     (where R and R' represent organic groups).
 Initial concentration of experiment 1:[OH−]0 = 0.900 M
                                                           [RCOOR']0 = 0.0010 M
Initial concentration of experiment 2:[OH−]0 = 0.0015 M
                                                          [RCOOR']0 = 0.600 M
The overall rate law is: −d[RCOOR′]/dt=k[RCOOR′]^n[OH−]^m
 and I found that n and m are both 1 and the pseudo constants are 35.8(for RCOOR') and 23.9(for (OH-).

I need help on finding the overall rate constant (k).
Thanks in advance