Explanation:
since you know already that it is a linear equation with a constant change rate (slope), you don't know the equation itself yet ?
you found the change rate (slope).
it is x goes up by 2, and y goes down by 6.
the slope is the ratio y/x representing the y and x changes, and it is always the factor of x.
"down" or "left" means "-","up" or "right" means "+".
the slope here is therefore
-6/2 = -3/1 = -3
so, we know the line function looks like
y = -3x + b
to get b we use one of the x y pairs like (1. 4)
4 = -3×1 + b
7 = b
and the full line function is
y = -3x + 7