Puzzle 17
Without using any reference material can you find the hidden countries? In each case, the letter indicates the first letter of the country in question, the number represents the number of letters in the country. For example, E7 would be England.
Z6, L10, I9, E7, B6, J7, P8, M10, P4, F4
Puzzle 18
Can you find a word that means perimeter …
… and by adding a letter A another word is formed that means a lodger?
Puzzle 19
Can you make this equation correct by moving exactly one matchstick?

Note: this puzzle is not interactive, and the matchsticks cannot be moved. The matchstick layouts for each digit are:
Puzzle 20
Can you find the country hidden in the following sentence:
Alex's aches and pains felt worse because of swollen glands that had flared up during the night, perhaps a tonic would help?