where m is the slope and is the point which the line passes through so to to find the equation of line which passes through the point
(5 , -4) it means the point should satisfy the equation which furthermore means that the point lies on the lie so we can replace y1 with -4 and x1 with 5 and since we have m = -1 we can thus find b and rewrite the equation like this:
since we need it point-slope form we leave it like this