#### Explanation:

The formula for pay rate is $r = \frac{p}{t}$ where $r$ is the pay rate, $p$ is the actual pay and $t$ is the time worked.

Substituting the actual pay and time worked for each of the examples gives us:

r_1 = ($315)/(3hr) =$105/(hr)

r_2 = ($525)/(5hr) =$105/(hr)

r_3 = ($735)/(7hr) =$105/(hr)