Well, let's see. My main problem here is how to lay it out clearly for you.
-- Do you remember the definition of a 'radian' ? A radian is an angle, that's
just the right size to cut one radius-length arc out of the curve of the circle.
-- So every radian of spin moves the tip of the propeller a distance that's
equal to the radius of the circle.
-- Now the radius of the circle that the tip of the propeller traces
is the length of the propeller blade ... 22.5 cm .
-- 130 radians per second means the tip of the propeller is traveling
the length of the circle's radius 130 times a second.
-- (130) x (22.5 cm) = 2,925 centimeters/second = 29.25 meters/second.