What events, conditions and actions I should use for this case? I use "commerce" and "commerce stock" modules, I created a list with products and a few extra fields in Product types:
- Image
- Deposit 1 Stock
- Deposit 2 Stock
- Deposit 3 Stock

I created a view (table - http://ucreateawebsite.com/DRUPAL/dalexgrup/pt)  with this fields: 
- Bulk Operations
- SKU
- Imagine
- Title
- Deposit 1 Stock
- Deposit 2 Stock
- Deposit 3 Stock

I have a problem in succeeding to create another stock field (the fourth - called TOTAL STOCK) and making it to automatically update when the other 3 fields are being changed. I want the fourth field to calculate and show me the sum of the other 3 fields.




Example 1 *
Deposit 1 Stock -> 15
Deposit 2 Stock -> 15
 Deposit 3 Stock -> 15


     TOTAL STOCK -> 45




Example 2 *
Deposit 1 Stock -> 10
Deposit 2 Stock -> 05
 Deposit 3 Stock -> 01


     TOTAL STOCK -> 16

This TOTAL STOCK field I should create in Product type like:
- Deposit 1 Stock
- Deposit 2 Stock
- Deposit 3 Stock ??????

Then I should create a rule? What events, conditions and actions I should use? 

Thank you.
I found the answer: 

For Event I used:

 1. After updating an existing commerce product

For Conditions I used:

1. Entity has field - Parameter: Entity: [commerce-product], Field: field_stock1

2. Entity has field - Parameter: Entity: [commerce-product], Field: field_stock2

3. Entity has field - Parameter: Entity: [commerce-product], Field: field_stock3

4. Entity has field - Parameter: Entity: [commerce-product], Field: field_totalstock

For Actions I used:

1. Calculate a value - Parameter: Input value 1: [commerce-product:field-stock1], Input value 2: [commerce-product:field-stock2]; Provides variables: Calculation result for Stock1  and Stock2 (stock1_plus_stock2_result)

2. Calculate a value - Parameter: Input value 1: [stock1-plus-stock2-result], Input value 2: [commerce-product:field-stock3]; Provides variables: Calculation result for stock1-plus-stock2-result and Stock3 (stock1_plus_stock2_result_plus_stock3)

3. Set a data value - Parameter: Data: [commerce-product:field-totalstock], Value: [stock1_plus_stock2_result_plus_stock3]

You can see what I wrote here -> http://ucreateawebsite.com/DRUPAL/dalexgrup/pt