Answer
I would need 0.72 L of solution to obtain 86.0 g of $KOH$.
Work Step by Step
$12\%$ (m/v) $ KOH $ solution : $$ 12 \space g \space KOH = 100 \space mL \space solution$$
$$86.0 \space g \space KOH \times \frac{100 \space mL \space solution}{12 \space g \space KOH} \times \frac{1 \space L}{1000 \space mL} = 0.72 \space L \space solution$$
