Which expression has a value of −9? (−12)−3

12−(−3)

(−12)−(−3)

3−(−6)

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

Change negative exponents to positive, then solve

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)