y- intercept = 20
y = [tex]\frac{3}{5}[/tex]x + 10 has slope m = [tex]\frac{3}{5}[/tex]
The perpendicular slope = -[tex]\frac{1}{m}[/tex] = - [tex]\frac{1}{\frac{3}{5} }[/tex] = -[tex]\frac{5}{3}[/tex]
perpendicular equation is y = -[tex]\frac{5}{3}[/tex] x + c
where c is the y-intercept
to find c substitute (15 , -5) into the equation
-5 = - 25 + c ⇒ c = - 5 + 25 = 20
y-intercept of perpendicular line is 20
