Answer:
40.7465

Step-by-step explanation:
The first step for solving this problem is to convert the units from gallons to cubic feet and from millimeters to cubic feet:
1 gallon = 0.133681 cubic feet
10 mm = 0.001 m = 0.0032808 ft
The second step is to divide the volume (the gallon of paint) by the coat thickness. This returns the area.

This is the approximate area that the gallon of paint will be able to cover.