To simplify \(37x + 27x\), you can combine the like terms by adding the coefficients together:
\[ 37x + 27x = (37 + 27)x = 64x \]
Therefore, the simplified expression is \(64x\).
None of the provided responses match this result, suggesting either the options were incorrectly listed, or additional context may be necessary. Based on standard operations, the simplified form is indeed \(64x\).