###Human: In a restaurant, a burger costs $9, and a pizza twice as much. How much would cost one pizza and three burgers?, ### Assistant: One pizza costs twice as much as the burger, which means 9 * 2 = $18.
Three burgers would cost 9 * 3 = $27.
So one pizza and three burgers would cost in total 18 + 27 = $45. 
 So the answer is :  45