Lisa made 6 sandwiches in 15 minutes. At that rate, how long will it take her to make 15 sandwiches ?

37.5 minutes

Step-by-step explanation:

You must find the rate at which she can make sandwhiches and use that to find your answer

Ok, so we know she can make 6 sandwiches in 15 minutes. So, in 30 minutes she can make 12 sandwiches. It takes her 2.5 minutes to make one sandwhich. Therefore for another 3 sandwiches it would take 7.5 minutes.

Answer: 37.5 minutes to make 15 sandwiches