Sharon and Ramla frequently mow their grandfather's yard. Working at her normal pace, Sharon can mow the yard in 5 hours. When Sharon and Ramla work together, each at her own normal pace, they can mow the yard in 3 hours. Yesterday, Ramla mowed the yard by herself. Given that Ramla was mowing at her normal pace, how long, in hours, did it take for Ramla to mow the yard?