Kenny and his mom are planting vegetables in their garden. Kenny has finished planting 3 rows of carrots so far and is planting new rows at a rate of 5 rows per hour. His mom has finished 9 rows of tomatoes and will continue planting at 4 rows per hour. Once the pair get to the point where they have finished the same number of rows, they will take a break and decide what to plant next. How long will that take? How many rows will they each have completed?