Question

http://i.imgur.com/oyYXNyh.png

Answer 1

first you need to work out how long it will take hime to fall from 18m high to ground (given that he started at 50m)

He needs to travel 10m horizontally in that time if he is to reach the pond

So you need to work out th ehorizontal velocity required to achieve this distance in the time available.

THEN
when he throws the bag he will gain horizantal vleocity keeping 'conservation of momentum' (in horizontal direction)

so 100 V = 1 v

where V is the velocity required for the man to reach the pond and v is the velocity of teh bag

(PS - I don't hold out much hope for him!)