Combine similar data from multiple sheets

I have a workbook with 4 sheets (call them Q1, Q2, Q3, Q4). Each sheet contains ~38,000 rows of data.

I need to combine all 4 sheets into one single sheet, but in the process I need to combine similar data that occurs over all 4 sheets. Similar data would be all of the following being equal:
1. Sales Rep Number
2. Account Number
3. Invoice Number

For example (example 1)
............Sales Rep............Account Number..............Invoice Number..........Sales Amount
Q1.......Mike....................12345...............................TX-EX34.....................10,000
Q3.......Mike....................12345...............................TX-EX34.....................20,000
Q4.......Mike....................12345...............................TX-EX34.....................50,000

After combining data, I would have one single line as follows:
............Sales Rep............Account Number..............Invoice Number..........Sales Amount
............Mike....................12345...............................TX-EX34.....................80,000


For example (example 2)
............Sales Rep............Account Number..............Invoice Number..........Sales Amount
Q3.......Jim.......................45774...............................PRS-ET99...................45,000
Q4.......Jim.......................45774...............................PRS-ET99...................15,000

After combining data, I would have one single line as follows:
............Sales Rep............Account Number..............Invoice Number..........Sales Amount
............Jim.......................45774...............................PRS-ET99...................60,000


I have searched all over the forums, but haven’t found anything that is similar to what I am looking for. I have attached a spreadsheet with sample data, which includes the desired output. Any assistance is appreciated. Thanks.