# How much work does it take to raise a 8 kg  weight 3 m ?

$W = F \Delta x \implies {\int}_{a}^{b} F \mathrm{dx}$
In your case F = mg; m = 8 kg; g = 9.81 m/s^2; and Deltax = 3 m
$W = 8 \times 9.81 \times 3 \approx 235 J$