A the slope of the line is 1
to calculate the slope m , use the ' gradient formula '
m = ( y₂ - y₁ ) /( x₂ - x₁ )
where (x₁, y₁ ) = 6, 3) and (x₂, y₂ ) = (9, 6)
m = [tex]\frac{6 - 3}{9 - 6}[/tex] = [tex]\frac{3}{3}[/tex] = 1
