title: How to create add and subtract buttons to track inventory
body: <p>I've been searching for similar solutions out there but am coming up short so far. Here is what I want to accomplish:</p>
  
  <p>I need to come up with a basic solution to sync inventory quantities at the end of each day. We take physical counts of inventory sold throughout the day but need something to log these changes and share between users. I would like to utilize two buttons (click one to subtract amount of items sold at the end of the day and click one button to add newly received inventory). </p>
  
  <p>This is how my sheet is set up:</p>
  
  <p>Col A:   Product Tag<br>
  Col B:   Product sku<br>
  Col C:   Amount Sold Today<br>
  Col D:   Total Inventory Quantity<br>
  Col E:   Add New Inventory<br></p>
  
  <p>Column D will be pre-populated with initial inventory counts. At the end of each day, I would like to go down my product list and fill in the amount of each item sold that day in Column C. Once Column C is fully populated, I would like to click the "subtract" button and have Column C subtracted from Column D.</p>
  
  <p>On the other side, once we receive new stock of an item I would like to enter these counts into Column E. Once this column is fully populated, I would like to click the "Add" button and have Column E added to Column D. Ideally once the add or subtract function has been completed, columns C or E will be cleared and ready for the next days entry.</p>
  
  <p>I already have designed my buttons, I just need help coming up with the scripts to accomplish this.</p>