Which expression is equivalent to (x-4y/x-9y5)-2? assume x≠0 y≠0

The difference of 2 numbers is 21 and the quotient of the equation is 4 then what are the two numbers?

When only separate discreet points are graphed it is called?

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)