I just want to add a form to a product and after I check the services in that form the amount increases. image of the page in the Picture the product price is 7$ but when I add the service it added 10$ then the amount become 17$. any solution for this?
Your looking for product variations. Here are the official docs.
Product attributes are the descriptors we use to define kinds of products. For example, we could describe a tshirt by the color and size. These attributes mean that in the real physical world your store may only carry one red shirt, but you have three sizes or three "variations." Commerce software must deal with product variations in a flexible way. Here's how Drupal Commerce abstracts it:
Product Types. A product type is a specific bundle based on a custom product entity. Each bundle can have fields attached to it, including pictures and other kinds of information.<
Product "Informational" Fields. Any field on a product can be a simple "informational" field. Typical informational fields include an image of that specific configuration of a product. For example, if you sell a tshirt with a cool print in multiple colors, each product with a different color could have an image field that, when displayed on the product display node, will change when you select different attributes (like color).
Product "Attribute" Fields. Any field on a product type with a defined list of options (list of text options, list of taxonomy terms, list of colors). The attribute fields are special because of the way they turn into selection widgets on a product display. Often you will pair an attribute field (like a color dropdown) with an information field (like an image field) to let the user "select" the blue tshirt and the Drupal Commerce system will quickly load the picture associated with the blue product.
Product Displays. If needed at all, these are groupings of products. You can reference any type and number of products on a product display. In order to make use of product displays, we recommend only showing one type of product per product display. The product display is where you typically see the product with drop downs to "configure" or "order" the right kind of product.
For the different pricing of the variations refeer here: Automatic product variations pricing.