6b-(4b-(2b-5))

To simplify the expression \( 6b - (4b - (2b - 5)) \), follow these steps:

1. Start with the innermost parentheses: \[ 2b - 5 \]

2. Substitute \( 2b - 5 \) back into the expression: \[ 6b - (4b - (2b - 5)) = 6b - (4b - 2b + 5) \]

3. Simplify \( 4b - 2b \): \[ 4b - 2b = 2b \]

4. Now the expression looks like this: \[ 6b - (2b + 5) \]

5. Distribute the negative sign: \[ 6b - 2b - 5 \]

6. Combine like terms: \[ (6b - 2b) - 5 = 4b - 5 \]

So, the simplified expression is: \[ \boxed{4b - 5} \]