Answer:
it's being divided by -5
Step-by-step explanation:
-5m= -40
m=8
Answer: Tammy's sample may not be vaild because she surveyed the students only from her class and it is likely that other classes might not like the subject maths. She might get the accurate results by surveying a larger number of people in the school instead of just her class.
199.
the z score for the 90th percentile is 1.28, so you can solve the equation

which gets you the 199
5:3
5 to 3
5/3
Is that what you are looking for?