sarah has already knit 17 centimeters of a scarf, and canknit 1 centimeter each night. How many nights will sarah have to spend knitting in order to knit a total of 34 centimeters of scarf?

17 nights.

Step-by-step explanation:

The total length of the scarf that should be knitting = 34 cm

Sarah has already knit 17 centimeters of a scarf.

So, the remaining = 34 - 17 = 17 cm

Sarah can knit 1 centimeter each night.

So, the number of nights will Sarah have to spend knitting = 17/1 = 17 nights.