Answer
infinitely many; $1-t$; 0, 4, -4
Work Step by Step
Since the graphs are the same, there are infinitely many solutions.
To find the slope-intercept form of the equation, we alter the equation as follows:
$x + y = 1$
$y = 1 - x$
When $x = t$, $y = 1 - t$.
Using this equation, plug in 1, -3, and 5 for t and we obtain the results 0, 4, and -4.