1. 7

2. 13

3. 34

4. 78

5. 14

6. 4

7. a. 50 pigs     b. 20 horses      c. 1280 animals

8. a. 28   number x 3 + 1         b. 13   number ÷ 2 + 6        c. 20  (number – 4) x 2

9. Four: (this works if Alice’s sister is married to Alice’s husband’s brother. The mother of both men is Alice’s mother’s sister and married to Alice’s paternal uncle)

10. The 400 litre barrel:

(Customer 1 buys 300 + 360 litres = 660 litres of wine. Customer 2 buys 320 + 380 + 620 = 1320 litres 0f wine. This leaves the 400 litre barrel which must contain beer)