Rosie can run 10 miles per hour for 3 hours. After that, she runs 5 miles per hour. How many miles can she run in 7 hours?
For the first 3 hours, Rosie runs 10 miles per hour, so she runs 10*3=<<10*3=30>>30 miles.
However, she still has 7-3=<<7-3=4>>4 hours left to room.
For the next 4 hours, she runs 5 miles per hour, so she runs 5*4=<<5*4=20>>20 miles.
In total she runs 30+20=<<30+20=50>>50 miles.
#### 50