How many miles of O2 are required to react completely with 3.5 mols of H2

Which of the following questions is a statistical question? (2 points) how many professional sport leagues are there? where do the professional sport leagues play? how many hours of professional training took place over the weekend? how many hours do you spend each week training for a sports league?

Simplify (a/b - b/a) times (a - a^2/a+b) a - a^2/a=b is a mixed number

7. if the value of x varies directly with the value of y, and x = 3 when y = 21. what is the valu y, and x = 3 when y = 21. what is the value of x when y = 105?