A balloon was moving upwards with a uniform velocity of $10 \mathrm{~m} / \mathrm{s}$. An object of finite mass is dropped from the balloon when it was at a height of 75 m from the ground level. The height of the balloon from the ground when object strikes the ground was ground was around: (takes the value of $g$ as $10 \mathrm{~m} / \mathrm{s}^2$ )