When she collected 180 cans she kwew she had reched 60% of her goal

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?

One line passes through (-7,-4) and (5,4) . another line passes through the point (-4,6) and (6,-9)

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'