Which of the following statements best describes the graph of x + y = 3? it is a line joining the points whose x- and y-coordinates add up to 3. it is a line joining the points whose x- and y-coordinates add up to 6. it is a line which intersects the x-axis at (3, 3). it is a line which intersects the y-axis at (3, 3).

Any graph is defined by a given function. A graph of x +y =3, may be described as a line joining points such the sum of x-coordinate and the y-coordinate is 3. These are points such as (1,2), (2,1), (3,0) and so on such that the satisfy the equation of the line. 

It is a line joining the points whose x- and y-coordinates add up to 3.
   Let's look at the options and see what does and does not make sense for the expression x + y = 3.

   It is a line joining the points whose x- and y-coordinates add up to 3.
 * This pretty much describes it and is the correct answer.

   It is a line joining the points whose x- and y-coordinates add up to 6.
 * I don't see any 6's in the equation, nor do I see anything that might become a 6. This is a bad choice.

    It is a line which intersects the x-axis at (3, 3).
 * This option doesn't make sense as an answer to ANY question. If it intersects the x-axis, then the y value HAS to be 0. And it's said to be a 3 which is nonsense. Definitely a bad choice.

   It is a line which intersects the y-axis at (3, 3).
 * Another nonsense choice. If it intersects the y-axis, the x value has to be 0 and it's not. So another horrible choice.

It's like discovering the answer to a puzzle. the purpose in solving an equation is to find the value or values of the variable that makes it a true statement. any value of the variable that makes the equation true is called a solution to the equation.