The Total Revenue Function (In Dollars) for a Blender Is

The total revenue function (in dollars) for a blender is , where x is the number of units sold. What is the average rate of change in revenue R(x) as x increases from 20 to 30 units? ​

A) $254.60 per unit
B) $59.80 per unit
C) $48.20 per unit
D) $49.80 per unit
E) $49.00 per unit