An electric company charges a certain rate per kilowatt-hour (\text{kWh})(kWh) of electricity used and an administrative fee of
\$3.50$3.50. The company charged Zhao \$63.25$63.25 for using 800\,\text{kWh}800kWh of electricity. Zhao uses the equation, 63.25=800r+3.5063.25=800r+3.50 to represent the situation. What does the variable rr represent in the equation