You got the point-slope equation of a line
y-1= -(x-12)
y-y coordinate of the point= slope (x- x coordinate of the given point) so the point is (1,12) and slope -1
The slope intercept form is y =mx+b that means y= slope• x + y intercept (where the graph touches the y axis)
We know the slope from previous equation as being -1 and we need to see when x=0
y=? to get the point (0, y intercept)
We know, y-1=-(x-12) so when x=0 we get
y-1=-(0-12); y-1=12; y=12+1=13
Our intercept is (0,13)
Our equation is y= -x +13
