Brain Teasers and Puzzles 

Workings

Hint
I bought at least 6 of each stamp.

Answer
Six lots of 4p, 7p. and 19p, and ten lots of 5p and 12p.

Reasoning
For three denominations of stamps, I was asked to buy 6 of each, and for the other two denominations, I had to buy 10 of each.

So I had to buy at least 6 of all five denominations.

This would be for a total of 6 x (4 + 5 + 7 + 12 + 19) = 282p = £2.82.

The remaining 68p has to buy the remaining 8 stamps – 4 of each of the two remaining denominations.

If we just bought 1 of each of the two remaining denominations they would have cost 68 / 4 = 17p.

So the two remaining denominations must have been 5p and 12p.

Double-Checking
 6 x 4  =  24
10 x 5  =  50
 6 x 7  =  42
10 x 12 = 120
 6 x 19 = 114

For a total of 24 + 50 + 42 + 120 + 114 = 350p = £3.50.

Workings

Hint
Look at the first and last letters.

Answer
2,300 miles.

Take the alphabetic position of the first and last letters, add them together and multiply by 100. S = 19, D = 4, 19 + 4 = 23, 23 x 100 = 2,300.