At the equator (0°), a given point on earth's surface travels about kilometers per hour.

1,600.   
So we have the planet earth, which has a radius of roughly 3960 miles. The formula for Circumference is 2*π*r. 2* π* 3960 ≠24881 miles. We have the Rate of Rotation is roughly 24881 miles. So take the Rate of Rotation and divide it by 24 and we get roughly 1037 MPH. then take this and multiply by 1.61 km/hr so we have 1660 km/hr.

Well, a and b together would be negative. b alone would also be negative.