Plz help :] it's for my geometry class! It'd due tomorrow!

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?

This is so hard and it’s for a test

What is the rate of change of a line that passes through (2,-5) and (6,-2)?