a gallon of paint will 640 square feet of wall space. If I plan to paint a room whose walls measure 2,560 square feet, how many gallons of paint will I need?

Question

How to setup equation and how to solve it step by step 

Answer 1

The question is how many 640 sq feet go into 2560 sq. feet.

2560 sq ft / 640 sq ft/gallon = 4 gallons

 

Looking at it a slightly different way:

2560 sq. ft x 1 gallon/640 sq. ft = 4 gallons

 

In reality, one would want to get more than 4 gallons to allow for extra.