Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

What does this rebus puzzle means ?

There is a basket full of hats. Three are white and two are black. Three men, Tom, Tim, and Jim, each take a hat out of the basket and put it on their heads without seeing the hat they selected or the hats the other men selected. The men arrange themselves so Tom can see Tim and Jim’s hats, Tim can see Jim’s hat, and Jim can’t see anyone’s hat. Tom is asked what color his hat is and he says he doesn’t know. Tim is asked the same question, and he also doesn’t know. Finally, Jim is asked the question, and he does know. What colour is his hat?

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

Jack and Joseph are well-known golf rivals. One Day during a match, they were level at a score of 30. Jack hit a bad shot and Joseph added 10 to his score. Joseph then hit an awesome shot and he won the game.

How ?

What do you see in the image below

During which month do people sleep the least?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

In the image given, you can find several triangles. Can you count them all?

Why did Navjot Singh Sidhu put the new January calendar in the freezer