In a two digit number, the tens digit is twice the ones digit. The difference of the ones digit and half the tens digit is 0

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

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)

Tobias gold sells computers at the office center he's guaranteed a minimum salary of $1,959 per month plus 6.3% commission on total sales how much in total sales is he