Help with setting the rpm

Can someone send a line of code that shows how to set a specific motor at an exact rpm. We use green motors so 200 rpm.
I have this but not sure it is working.

mtr_front_right.spin(directionType::fwd, 200, velocityUnits::rpm);

That line looks fine to me. Can you explain what your specific problem is?

hey thanks for the reply, but I actually figured out what my problem is

Can you please tell us the answer so if someone else has the same problem we can suggest the correct answer?