Answer:
He can make 120 burgers in 30 minutes
Step-by-step explanation:
Set up a proportion where x is the number of hamburgers he'll make in 30 minutes:
[tex]\frac{4}{1}[/tex] = [tex]\frac{x}{30}[/tex]
Cross multiply:
x = 120
So, he can make 120 burgers in 30 minutes.