[ Answer ]
[tex]\boxed{3a \ + \ 8b}[/tex]
[ Explanation ]
Combine Like Terms (Simplify): 6a + 8b - 3a
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Group Like Terms
6a - 3a + 8b
Add Similar Elements
6a - 3a = 3a
Add Items Together
3a + 8b
[tex]\boxed{[ \ Eclipsed \ ]}[/tex]
