This math problem has got me stumped: Carly is making burgers for a neighborhood BBQ. Each burger needs to be cooked for 4 minutes on each side. Carly can fit 5 burgers on the grill at once. If half her 30 guests want 2 burgers and the other half each want 1, how long will it take Carly to cook all the burgers?
Can you show me the way?