How do you make a precise estimation of painting expenses for a Living Room in St. Gallen with excluding ceilings, 2 doors, and 2 windows, covering an area of 10m x 7m?

Making a precise estimation of painting expenses for a Living Room in St. Gallen, excluding ceilings, 2 doors, and 2 windows, covering an area of 10m x 7m, involves accurately calculating CHF 398.00.

*) The calculations are approximate, based on a room height of 2.4m, and include one coat of paint. The price covers only the labor, excluding any services or materials.