Break down this math problem: A lot of people have been sick at Gary's workplace, so he's been working a lot of extra shifts to fill in for people. As a result, he's earned some overtime (where every hour after 40 he earns 1.5 times his normal wage.) His paycheck (before taxes are taken out) came out to $696. If Gary normally earns $12 per hour, how many hours did he work that week?