Hi there!

To begin, we must use the slope formula to calculate the slope of the line:

Plug in the coordinates:

Simplify:

Recall that the equation for a line in point-slope form is:
y - y1 = m(x - x1)
Plug in coordinates into the equation along with the slope:
y - (-2) = -1(x - 9)
Simplify:
y + 2 = -x + 9
y = -x + 7