solve ln(5/3)

That would be ln5 - ln3.

Use log tables, a pocket calculator or Google to calculate the value.

http://www.google.com/#sclient=psy&hl=en&q=ln(5%2F3)&aq=&aqi=&aql=&oq=&gs_rfai=&pbx=1&psj=1&fp=567204dc07534ddc