A family are out on a hike and reach a river which they need to cross. There is a canoe which can carry 100 kg.
The father weighs 90 kg, the mother weighs 80 kg, the elder child weighs 60 kg, the younger child weighs 40 kg, and they have a dog that weighs 20 kg.
Assuming that the humans can all paddle the canoe, how do they cross the river?
Answer on 9.00 on Monday