Find the equation of the line that is parallel to the line x + y - 3 = 0 and that passes through the point (2.3)

1. Rewrite the given line equation in slope-intercept form to find its slope:
x + y - 3 = 0
\Rightarrow y = -x + 3

2. The slope of the given line is:
m = -1

3. A parallel line will have the same slope. Using the point-slope form of the line equation with the point (2, 3) and slope -1:
y - 3 = -1(x - 2)

4. Simplify the point-slope form to slope-intercept form:
y - 3 = -x + 2
\Rightarrow y = -x + 5

5. Convert back to standard form:
x + y - 5 = 0

So, the equation of the line parallel to the given line and passing through the point (2, 3) is:

x + y - 5 = 0