Answer:
It will take 5.4 hour to paint 720 square feet
Step-by-step explanation:
The question should be like this"Andy painted 400 square feet in 3 hours. How long would it take him to paint 720 square feet?"
In 3 hours = 400 square feet is painted
1 square feet is painted in [tex]\dfrac{3}{400}\ h[/tex]
To find time to paint 720 square feet multiply the above term by 720 as follows :
[tex]720\ ft^2=\dfrac{3}{400}\times 720\ h\\\\=5.4\ h[/tex]
So, it will take 5.4 hour to paint 720 square feet.