Soluciones:

ALL ROADS LEAD TO... Starting at this intersection, one of the roads leads back to his home town. Therefore, all he has to do is put up the sign with the corresponding pointer in the direction of the road that he came on, and the rest of the pointers will then all point in the right direction.

HIKER'S SHARE: The 3rd hiker is right. Each of them has eaten 2+2/3 sandwiches (8 divided by 3). The 1st hiker gave the 3rd, 2+1/3 (7/3) while the 2nd hiker gave the 3rd 1/3 of a sandwich; therefore the 1st hiker should pay 7 dollars and the second should get one dollar.

TIPPING THE SCALES: Jane weighs 42 pounds and David 24 pounds. Together they weight 64 pounds.

AN ORNITHOLOGICAL PROBLEM: If all but four of the birds are canaries, that means that the total number of parakeets and sparrows must be four. We can deduce that there are two canaries, two parakeets and two sparrows.