A ramp is easier for a person to go up or down on because it is just higher sloped ground. For a person with crutches, a ramp does not have any abnormal steps for them to try and get over with one leg.
Since he gives the dog 3 liters of water and 500 grams of food a day we know that on the fifth day the dog will have gotten 15 liters of water and 2,500 grams of food.
