Step-by-step explanation:
Hey there!
Let the unknown slope be M2.
The given equation is;
15x + 12y = -144
From equation;
[tex]slope( m) = \frac{ - coeff. \: of \: x}{coeff. \: of \: y} [/tex]
[tex]m = \frac{ - 15}{12} [/tex]
[tex]m = \frac{ - 5}{4} [/tex]
For the condition of perpendicular lines;
[tex]m \times m2 = - 1[/tex]
[tex] \frac{ - 5}{4} \times m2 = - 1[/tex]
[tex] - 5m2 = - 4[/tex]
[tex]m2 = \frac{ - 4}{ - 5} [/tex]
Therefore, the slope is 4/5.
Hope it helps....