Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

Forwards I am heavy, backward I am not. What am I?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

John was drowned by he was not wet. How?

Count the number of squares in the picture below.

Christina is practising her dance steps along with her friends. In a particular sequence, all of them form a row. At that point, Niharika is standing in the 4th position from either end of the row.
Can you find out how many girls are practising together?

I know a 5-digit number having a property that With a 1 after it, it is three times as large as it would be with a one before it.

Guess the number?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?