Simplify 6 - 4[x + 1 - (y + 3)] + 5y.

First simplify inside the brackets: x + 1 − (y + 3) = x − y − 2. Distribute −4 to get −4x + 4y + 8, then combine with 6 + 5y: 6 + 8 − 4x + 4y + 5y = 14 − 4x + 9y. The simplified expression is 14 − 4x + 9y, choice C.

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