What portion of the walls of the large room has been painted?

Question

Katrina and Leigh are painting the walls of a large room. They mixed 3 gallons of blue paint with 7 gallons of white paint for a total of 10 gallons of paint. They run out of paint. They estimate that they need 1/2 a gallon to finish. What portion of the walls of the large room has been painted??

 

-In class we usually don't use formulas but all answers are appreciated!! 

Answer 1

Assuming that the paint is uniformly applied,

They did 10 / 10.5, or 0.952380952 of the room