Can you solve this picture maths equation?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

In the picture that is attached with this question, you can find a square which comprises of four little squares inside it. Consider this square to be made with matchsticks. You have to remove two matchsticks such that only two squares remain instead of five.How will you do it ?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

Our product and our sum always give the same answer. Who are we?

Why is a river so rich ?

Three cars are driving on a track that forms a perfect circle and is wide enough that multiple cars can pass anytime. The car that is leading in the race right now is driving at 55 MPH and the car that is trailing at the last is going at 45 MPH. The car that is in the middle is somewhere between these two speeds.
Right now, you can assume that there is a distance of x miles between the leading car and the middle car and x miles between the middle car and the last car and also, x is not equal to 0 or 1.
The cars maintain their speed till the leading car catches up with the last car and then every car stops. In this scenario, do you think of any point when the distance between any two pairs will again be x miles i.e. the pairs will be x distance apart at the same time ?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

How many times can you subtract the number 5 from 25?