A balloons is moving vertically up with a velocity of  $4{\text{\hspace{0.17em}ms}}^{-1}$.  When it is at a height of ‘h’, a body is gently released from it.  If it reaches the ground in 4s, the height of the balloon, at the instant the body released, is $(g=10{\text{\hspace{0.17em}m/s}}^2)$