Path A-K Length and Net Area
The path length, in this case, is the plate width (12") less two EFFECTIVE HOLE DIAMETERS:
EFFECTIVE HOLE DIAMETER = bolt dia. + 1/16" for std hole + 1/16" damage allowance
Path Length = 12" - (2 hole diameters)*(3/4" + 1/8") = 10.25 inches
The net area equals the path length times the plate thickness:
Net Area = (10.25")(.375") = 3.85 in2