How can I compute for the relative rate? The only given is the concentration and time per trial.

Answer 1

I forgot to add the details but here it is

Trial - Concentration - time
1 - 1 M - 21.5 s
2 - 2 M - 21 s
3 - 1.5 M - 19 s
4 - 0.5 M - 21 s

Answer 2

Take the average of the trials for M and for time
rate = M/s
If this is an experiment you've done I must say the agreement isn't very good between trials.