Earth's Rotational Velocity: Find Linear Velocity

[physics123456]

Homework Statement

Find the linear (or tangential) velocity of a point on the Earth's equator in the frame of reference about a stationary rotational axis as it spins over the course of one day.

Homework Equations

The Attempt at a Solution

I do not understand what the frame of reference is?? If a frame of reference isn't given, how do i find the linear velocity?

 

[haruspex]

It means taking the Earth's centre as the origin of a non-rotating frame.