Here are the solutions:
1.
First, divide the line in 3 equal parts. The shoes are 10
Next take 10 + cat + cat = 20, so the cat is 5
Next take 5 + whistles + whistles = 13. So the whistles are 4.
That leaves you with: 10 + 5 x 4 = 30
2.
The second clock is 1 hour and 10 minutes behind the first.
The third is 1 hour and 20 minutes behind the second.
The fourth is 1 hour and 30 minutes behind the third.
So, the fifth clock should be 1 hour and 40 minutes behind the fourth.
It should be set at 5:35