Why is the rise the value for the numerator and the run the value for the denominator?

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Can someone plz me understand how to do these. plz, show work.in exercises 1-4, rewrite the expression in rational exponent form.[tex]\sqrt[4]{625} \sqrt[3]{512} (\sqrt[5]{4} )³ (\sqrt[4]{15} )^{7}\\ (\sqrt[3]{27} )^{2}[/tex]

When steve woke up. his temperature was 102 degrees f. two hours later it was 3 degrees lower. what was his temperature then?