Answer: The most cost effective company is Painting USA as it is cheaper comparatively.
Step-by-step explanation:
Since we have given that
Number of hours needed to paint Paul's house = 25 hours
Initial charges of Painting USA to evaluate the house = $75.00
Cost per hour of labor = $25.00
Total cost of Painting USA would be given by

And Upscale Home painting does not charge to evaluate the house.
Cost per hour by Upscale Home painting = $40.00
Total cost of Upscale painting would be

Hence, the most cost effective company is Painting USA as it is cheaper comparatively.