What is the property x + y = y + x

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours

Xy x xy if a and b are positive integers such that a*b=9 and b*a=72 what is the value of a/b

I'm confused on how to solve the triangle. can someone me ?