What are the three forms of linear equations?

The means and mean absolute deviations of the individual times of members on two 4x400-meter relay track teams are shown in the table below. means and mean absolute deviations of individual times of members of 4x400-meter relay track teams team a team b mean 59.32 s 59.1 s mean absolute deviation 1.5 s 245 what percent of team b's mean absolute deviation is the difference in the means? 9% 15% 25% 65%

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

Having a hard time understanding this question (see attachment).