Question

what line could be the graph of the points on the table:
x = 1,2,3
y = 5,3,1

Answer 1

The three points are collinear with slope m = (3−5)/(2−1) = −2. Using point-slope with (1,5):

y − 5 = −2(x − 1) → y = −2x + 7.

(Equivalently: 2x + y − 7 = 0.)