3а-7в-6а+8в

To simplify the given expression 3a - 7b - 6a + 8b, we need to combine like terms.

First, combine the like terms with variable 'a': 3a - 6a = -3a

Next, combine the like terms with variable 'b': -7b + 8b = b

So, the simplified expression is: -3a + b