Respuesta :
					                   17x -8.2y +3.1z , the subtraction flips the signs on the second set, and then you just add the same variables together.
					                
					                
					             
					                      7.8x - 3.4y + z
-(-9.2x + 4.8y - 2.1z)
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17x - 8.2 y 3.1z
					                
					                
					             -(-9.2x + 4.8y - 2.1z)
-------------------------------
17x - 8.2 y 3.1z
 
			                   
					                  