If you watch the walking dead at 12: 30,and then watch being human at 1: 45 how long did the walking dead episode last?

12:30 is 30 minutes away from 1 on the clock. 1:45 is 45 minutes from 1, with this we can simply add 30 minutes and 45 minutes. Which leaves you with 75. The episode lasted 75 minutes (or 1 hour and 15 minutes)