Step-by-step explanation:

Answer: 180
Step-by-step explanation:
Answer:
At most 25%
Step-by-step explanation:
The fraction of the distribution that can exceed n standard deviations from the mean is 1/n². For a standard deviation of 5 and a mean of 80, a score of 90 is (90-80)/5 = 2 standard deviations from the mean. Scores better than that can be at most (1/2)² = 1/4 = 25% of the total number of scores.
Your answer will be B) x=12
1)5x-3x
2) move 9 to the other side (change signs)
3)18+15-9
4) 2x= 24 (divide 2 from both sides
5)x=12
hope this helps
Use the pythagoras theorem
And the answer will be 36.