Does anyone know how to answer this problem?

How much force directed parallel to a horizontal surface is required to start a sled in motion given that the sled weighs 250 N and the person sitting on the sled weighs 100 N and the coefficient of static friction between the sled and the snow is 0.15. How much force will be required to keep the sled in motion if the coefficient of kinetic friction is 0.10. Please show the work with the answer. It will really help.