This question is asking the maximum speed of some point on a wheel.
Wheels are circular and the question doesn’t specify the angular or linear speed to calculate, we shall try to calculate both.

What we are given here is distance in centimeters from the axle to the point of concern. That distance is 15CM. Here 15CM is acting as a radius of the wheel. Since this is measuring an angular distance, we need to look for the circumference and the diameter of the point. 15*2= 30 the diameter. What is the circumference?

Angular speed is the rate at which a wheel turns. It is given in units like revolutions per minute, degrees per second, radians per hour on and on.

To calculate the angular speed you consider the point which is 15cm away from the axle all the points lying from the axle to the 15th cm on the tyre will rotate at an equivalent speed. This is true irrespective of the size of the tyre. Since we are talking about an object that is under an angular motion all the points lying on a given radius will have the same rotatory speed irrespective of the space of that time from the axle (centre).

The linear speed is the speed at the point on the outside of the object travels in its circular path. If v represents the linear speed of a rotating object, r its radius, and ω its angular velocity in units of radians per unit of time, the formula for this will be: 2πR * Rpm / 60! But here we are given just one instead of 2 to find the third. There we cannot actually complete the calculations.

If we consider the linear motion of that time which is 15cm faraway from the axle on the tyre, we’ve to imagine the space covered. Because the circumference of a circle that features a radius of 15cm. By this logic, the farther you move from the axle the more the linear distance covered. then
v=rω.

You can also read here how to calculate the number of milliseconds in a year.