I really need help pls help

15m is what percent of 60m; 3m; 30m; 1.5 km? the last one is km not m

3x + 4y = 5 x- 3y = -7 solve by substitution

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)