You can quickly change the price of items or packages when editing either from the Line Item Group in a project.
To update the price of an item in a project,
Navigate to the project
Click the three dots to the right of the line item to "Edit" it
Click "Override Amount"
Enter your cursor into the pricing field and use the following symbols to take action
use "*" to multiply the current price of an item
use "/" to divide the current price of an item
use "+" or "-" to add or subtract from the current price of an item
Check out the GIF below to see how to do this in a project.
Pricing can only be changed using in-line calculations from within a project. It does not apply to items from the inventory tab.