Verified answer

I think you've made an error typing your question. 4 rev/s = 25 rad/s but NOT 25 rev/s = 4 rad/s.

Here is how we convert: we know that 1 revolution = 2 pi radians. Therefore 4 rev/s = (4 x 2 x pi) rad/s

Hint: what is the definition of a radian?

What is the definition of a revolution (a complete rotation...correct?)?

How many radii can be wrapped around the arc of a complete circle?

Similarily, how many radians are there in a revolution? Hint: exactly the same as the above.