Write a piecewise definition of the monthly charge s(x) (in dollars)

Write a piecewise definition of the monthly charge S(x) (in dollars) for a customer who uses x kWh in a summer month:

Energy charge (June -Septmenber):
$3.00 for the first 20 kWh or less
5.70 cents per kWh for the next 180 kWh
3.46 cents per kWh for the next 800 kWh
2.17 cents per kWh for all over 1,000 kWh