Mary earns $6 per hour as a waitress. Last week she took home her regular earnings of $6 per hour plus $188 in tips for a total of $326. Which equation can be used to find how many hours, h, Mary worked last week?

A. $326 = $6h + $188

B. $326 = $188h - $6

C. $326 = $6h - $188

D. $326 = $188h + $6