What is the total available static pressure for the ductwork for a system with the following specifications? Blower: 0.55 in wc total external static at design airfl ow Evaporator coil: 0.25 in wc static pressure drop at design airfl ow Filter: 0.1 in wc static pressure drop at design airfl ow Registers and grilles: 0.05 in wc static pressure drop at design airflow