Answer: 1
Explanation:
The given equation x + y = 3 can be rearranged to slope-intercept form, which is y = -x + 3.
To find the slope of this line, we can see that the coefficient of x is -1. Therefore, the slope of the line is -1.
To find the slope of a line perpendicular to this line, we need to take the negative reciprocal of the slope of the given line.
The negative reciprocal of -1 is 1/1 or simply 1. Therefore, the slope of a line perpendicular to the line x + y = 3 is 1.