A horse is trotting along pulling a sleigh through the snow. To move the sleigh, of mass

Question:

A horse is trotting along pulling a sleigh through the snow. To move the sleigh, of mass m, straight ahead at a constant speed, the horse must pull with a force of magnitude T.
(a) What is the net force acting on the sleigh?
(b) What is the coefficient of kinetic friction between the sleigh and the snow?