To find the sum for the given $x$ values (-3, 5, 8, 10), we simply add them together.

$\sum x = (-3) + 5 + 8 + 10$

Let's calculate this step by step:

$-3 + 5 = 2$ $2 + 8 = 10$ $10 + 10 = 20$

So, the sum of the given values is:

$\sum x = 20$

Would you like more details or have any questions? Here are some related questions for further exploration:

1. How do you calculate the sum of squares of numbers?
2. What is the sum of a geometric series?
3. How do you calculate the sum of an arithmetic series?
4. What are the properties of summation notation (∑)?
5. How do you handle negative values in summation problems?

Tip: When summing numbers, always double-check that you're including all values, especially when dealing with sequences or sets!