Weare asked to use the "point-slope" form of a line that has slope -5 and goes though the point (1, -7) on the plane.
Therefore we use the form:
y - yp = m (x - xp)
where "m" is the slope, and xp and yp are the coordinates of the point on the plane the line goes through. So in our case we have:
y - (-7) = -5 (x - 1)
now we proceed to remove parenthesis using distributive property:
y + 7 = -5 x + 5
and finally express the equation in slope-intercept form by isolating "y" on the left:
Subtract 7 from both sides and combine:
y = -5 x + 5 - 7
y = -5 x - 2