250 Lbs Across The River?

Two boys weighing 50 pounds each and their older brother weighing 100 pounds wish to cross a river. Their boat will only hold 100 pounds.

How can they all cross the river in the boat?

Find here how they can! 

Source 

Taking 250 Lbs Across The River.

What was the challenge? 

1. First 2 boys of 50 pounds should cross the river.

2. One of them should bring back the boat at other end.

3. A boy with 100 pounds should carry himself across the river with boat.

4. Other boy of 50 pounds waiting across the river now should bring back the boat again.

5. Now both boys of 50 pounds now should cross the river.