How much work would it take to push a  12 kg  weight up a  9 m  plane that is at an incline of  pi / 3 ?

$917.54 J$
$\text{Work done = change in potential energy }$
Now, change in potential energy = $m g h = m g l \sin \theta = 12 k g \times 9.81 m {s}^{-} 2 \times 9 m \times \sin \left(\frac{\pi}{3}\right) \approx 917.54 J$