The equation that represents the relationship between the number of square feet painted (y) and the number of gallons of paint used (x) can be expressed as follows:
 ,
,
where 
 represents the constant of proportionality.
 represents the constant of proportionality.
In this specific scenario, MaryAnne painted 600 square feet of wall space using 1 1/2 gallons of paint. To find the value of 
 , we can substitute the given values into the equation:
, we can substitute the given values into the equation:
 .
.
To solve for 
 , we can multiply both sides of the equation by
, we can multiply both sides of the equation by 
 :
:
 ,
,
 .
.
Therefore, the equation representing the relationship between the number of square feet painted (y) and the number of gallons of paint used (x) is:
 .
.