Find an equation of the line that x-intercept 6; y-intercept -6

The general format for equation of a straight line is:

y = mx + c

Where m = gradient,  c = y intercept = -6.

The point format is (x, y).

Note, the x intercept is the value of x, when y = 0.  Therefore, x intercept of 6, means at that point y = 0.  Therefore the point is (6,0).

Note, the y intercept is the value of y when x = 0.  Therefore, y intercept of -6, means at that point x = 0.  Therefore the point is (0,-6).

Gradient between  (6, 0)  and (0, -6).

Gradient, m  = (y2 - y1) / (x2 - x1)  =  (-6 - 0)/(0 - 6) = -6/-6  = 1

Gradient m = 1.

y = mx + c  = 1x + (-6) =  x - 6

y = x - 6.  That is the equation of the line

1195 was the store owner's profit.