we start with the equation y-y1 =m (x-x1) because we have m the slope = 1/4 and a point on the line with the coordinates (x1=-20, y1=-6) so,
y+6=1/4 ( x+20);
y=(1/4)x + 20/4 -6;
y= (1/4)x -1 and this is the equation in slope intercept form y=mx +b where the lope m= 1/4 and b= -1 the y-intercept
Answer y= (1/4)x -1