3hours worked for $12; 9 hours worked for $36

Given data: 3 hours of work for 12 dollars and 9 hours of work for 36 dollars.
Question : Let us show the unit rate of each given data, then solve for the unit rate. Which of the two is better?
Solutions:
First given = 3 hours of work for 12 dollars
=> 12 dollars to be divided with 3 hours
=> 12 / 3 =
=> 4 dollars / hour
Then let’s solve for the second given data = 9 hours of work for 36 dollars
=> 36 dollars will be divided with 9 hours of work
=> 36 / 9 = 4 dollars
=> 4 dollars / hour
Thus, the first and the second given data are equal