If you want the answer to the equation of the line, then the answer is: y = x.
Explanation: a line on a graph always has an equation of y = mx + b. In the equation, you are not supposed to replace x or y with anything. The m is the slope, or the degree of the line. You find the slope by doing the rise/run, or how many units the line went up divided by the amount of units the line went to a side. If it went up or right, the unit is positive, if it went down or left, the unit is negative. Right here, we see that the line rises 1 and runs 1, and 1/1 = 1, therefore the slope (or m) = 1. So now the equation is y = 1(x) + b, but 1(x) = x, so we could simply the equation to y = x + b. The b is the y coordinate that the line crosses at. In this equation, the line crosses at the y-coordinate 0. Therefore, we could say that the equation has no b or b = 0. y = x + 0 is the same thing as y = x. The answer is y = x.