Work = Force multiplied by the distance(or displacement)
If the velocity is constant then the acceleration of the object is zero.

Thus when we apply the equation

It remains

or equivalent
Explanation :
The forces acting on hot- air balloon are:
Weight, (W)
Force due to air resistance, (F)
Upthrust force, (U)
Its weight W is acting in downward direction. The upthrust force U acts in upward direction. When the balloon is moving upward, the air resistance is in downward and vice versa.
In this case, the hot-air balloon descends vertically at constant speed.
so, 
and 
so,
....................(1)
when it is ascending let the weight that it is releasing is R, so
..........(2)
solving equation (1) and (2)

2F is the weight of material that must be released from the balloon so that it ascends vertically at the same constant speed.
Answer: 110000
Explanation:
26/9=30.5555555556
30.5555555556 x 60=1833.33333333
110000 x 60=110000