Francesca has already knit 28 centimeters of scarf, and can knit 7 centimeters each night. How many nights will Francesca have to spend knitting in order to knit a total of 42 centimeters of scarf?

2 nights

Step-by-step explanation:

We need to find how many nights Francesca will have to spend to knit the rest of the scarf.

First, we have to find how much she has left to knit, and then find how many nights it will take her.

She has already knit 28 centimeters of scarf.

She wants to knit a total of 42 centimeters of scarf.

Therefore, the length of scarf left to knit is:

42 - 28 = 14 centimeters

She can knit 7 centimeters each night.

Therefore, the number of nights more she needs to knit 14 centimeters is:

14 / 7 = 2 nights

She will spend 2 nights to knit a total of 42 centimeters of scarf.