Invariant subspaces under linear transformation and its complexification

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The problem $77.6$ from Finite Dimensional Vector Spaces:

If $A$ is a linear transformation on a real vector space $V$ and if a subspace $M$ of complexification $V^+$ is invariant under $A^+$, then $M^\perp \cap V$ is invariant under $A$.

The problem states that $M^\perp \cap V$ is invariant, but my solution proves that $M \cap V$ is.

Let $x \in M \cap V$, then $Ax = Ax + i\cdot A0 = A^+(x + i\cdot0) \in M$, by the fact that $x + i\cdot0 \in M$ and $M$ is invariant under $A^+$.

Is my proof correct?