What is the equation for the sequence -5, 10, -15, 20, -25, 30..

First, you can see that the term changes sign each time. This means that it is multiplied by a negative number each time.

Then, you see only multiples of 5...

This means that the pattern is as such:

5 x -1
5 x 2
5 x -3
5 x 4
5 x -5
5 x 6

When you multiply 5 by odd numbers, you add the negative sign, and when it's an even number, you put the positive sign. Post what you get for the next term :)