During a lab exercise we measured different masses of a magnetic material on a scale while changing the strength of the magnetic field it was in. Afterwards we plotted the masses and the fieldstrength hoping to find a linear slope. Then we drew a linear slope by using linear regression and found the declination of the slope and it's error. However this error does not take into account that the values of the masses also have an error. How can I fin the total error of the declination with the errorin the measurements in mind?