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Not exactly. The way I think about it is that the portfolio is risk-adjusted, meaning that (returns excess of risk free rate) / (std dev) of the market must equal that of the portfolio.
Hence to use @exam_whiz‌’s convention,
(ERp – Rf) / sdp = (ERm – rfr) / sdm
Which you can rearrange into what @exam_whiz‌ shows in their answer.