Random Puzzles 

Workings

Hint
The sons row across first.

Answer
The two sons rowed to safety first, one son rowed back.
I rowed to safety and the other son rowed back to the island.
The two sons rowed to safety first, one son rowed back again.
My wife rowed to safety and the other son rowed back.
Finally, the two sons rowed to safety.

Workings

Hint
Something's wrong with the letter O, and the word 'oifoeront' is important to the answer.

Answer
15 different letters: acdefhilmrstvwy.

Reasoning
The sentences should read:

As you can see, my printer replaces every third letter with the letter 'o'.

How many different letters have been replaced?

Workings

Hint
How many miles did I travel?

Answer
I had lost 4 gallons.

Reasoning
I travelled at 50mph for 4 hours, which is 200 miles.

I used 25 gallons every 25 miles, so I used 8 gallons travelling those 200 miles.

I started with 12 gallons and used 8 gallons, so I lost the other 4 gallons.

Workings

Hint
You might need an old calculator.

Answer
Coil.

Reasoning
This is the only word that cannot be spelled using a calculator.

For example, if you enter 376616 into an old-fashioned calculator, and look at the number upside down, you can read GIGGLE.
376616  = giggle
7105    = soil
57738   = bells
378806  = gobble
4506    = gosh
5508    = boss
3704    = hole
5355378 = blesses
coil    = ????