Answer:
[tex]gradient \: of \: y = 3x - 5 \: is \: 3 \\ m = 3 \\ for \: perpendicular \: m {}^{.} \times m = - 1 \\ 3m {}^{.} = - 1 \\ m {}^{.} = - \frac{1}{3} \\ from \: \: y = mx + c \\ at \: (8,5) \: \: 5 = - \frac{1}{3} \times 8 + c \\ c = - \frac{15}{8} \\ hence \: \: y = - \frac{1}{3} x - \frac{15}{8} [/tex]
