## Basic College Mathematics (9th Edition)

1.$\frac{20 Dollars}{1 hour}$ i.e. Elena earns 20 Dollars per hour. 2. $\frac{0.05 hours}{dollars}$ i.e. Elena will take 0.05 hours to earn one Dollar.
Elena made Dollar 60 in three hours. 1. We need to find earnings in dollar per hour. First we try to put the detail in ratio as $\frac{60 Dollars}{3 hours}$ =$\frac{20 Dollars}{1 hour}$ i.e. Elena earns 20 Dollars per hour. 2. We need to find earning in hours per dollar. First we try to put the detail in ration as $\frac{3 hours}{60 Dollars}$ =$\frac{1 hours}{20 dollars}$ = $\frac{0.05 hours}{dollars}$ i.e. Elena will take 0.05 hours to earn one Dollar.