On saturday morning Pam walked for 2 hours and then ran for

On saturday morning, Pam walked for 2 hours and then ran for 30 minutes. If she ran twice as fast as she walked and she covered 12 miles altogether, then how fast did she walk?

rt+rt=d
r=2w
2w+1/2r=12
2w+1/2(2w)=12
3w=12
w=4
r=8
Reminder:
You are limited to one problem per submission.
No more than 4 submissions daily
No similar problems.