which number fills in the blank?

Answer:
The teacher assigned the research project and explained it would be due on Friday. However, the snow storm caused school to be cancelled for 2 days. As a result, the students did not have access to the materials they needed to complete the project. When the students returned to school, the teacher extended the deadline for the project. As a result, the students were able to complete their projects, even though they had missed two days because of the snow storm.