Explain how you know whether to add or subtract when you use the Distributive Property

Example: 4(5x+4y)                  YOU DON'T CHANGE THE ADDITION SIGN OR SUBTRACTION SIGN WHEN DISTRIBUTING. NO NEED TO CHANGE.  ONLY CHANGE WHEN  -4(5x+4y)             -20x-16y BECAUSE + AND - = -

Use the integer aogn, a positive (+ sign) or negative (- sign) before the number.