Un juego de llantas tiene un 40 % de descuento sobre su precio original, y se le aplica un descuento adicional del 20 % sobre el precio con descuento. ¿Qué porcentaje de descuento total tiene el juego de llantas, sobre su precio original?

Me with this assignment ! i only partially understand, so explain. also it's a work sample. at the championship bike race, steve and paula were fighting for first place. steve was 175 feet ahead of paula and had only 300 feet left to go. he was very tired and was going only 9 feet per second. paula was desperate to catch up and was going 15 feet per second. who won the bike race and by how far did she/he win?