Normal invariants of products (Ex)

Let $(f, \bar f) \colon M \to X$$\newcommand{\Z}{\mathbb{Z}} \newcommand{\R}{\mathbb{R}} \newcommand{\C}{\mathbb{C}} \newcommand{\N}{\mathbb{N}} \newcommand{\Q}{\mathbb{Q}} \newcommand{\F}{\mathbb{F}} \newcommand{\bZ}{\mathbb{Z}} \newcommand{\bR}{\mathbb{R}} \newcommand{\bC}{\mathbb{C}} \newcommand{\bH}{\mathbb{H}} \newcommand{\bQ}{\mathbb{Q}} \newcommand{\bF}{\mathbb{F}} \newcommand{\bN}{\mathbb{N}} \DeclareMathOperator\id{id} % identity map \DeclareMathOperator\Sq{Sq} % Steenrod squares \DeclareMathOperator\Homeo{Homeo} % group of homeomorphisms of a topoloical space \DeclareMathOperator\Diff{Diff} % group of diffeomorphisms of a smooth manifold \DeclareMathOperator\SDiff{SDiff} % diffeomorphism under some constraint \DeclareMathOperator\Hom{Hom} % homomrphism group \DeclareMathOperator\End{End} % endomorphism group \DeclareMathOperator\Aut{Aut} % automorphism group \DeclareMathOperator\Inn{Inn} % inner automorphisms \DeclareMathOperator\Out{Out} % outer automorphism group \DeclareMathOperator\vol{vol} % volume \newcommand{\GL}{\text{GL}} % general linear group \newcommand{\SL}{\text{SL}} % special linear group \newcommand{\SO}{\text{SO}} % special orthogonal group \newcommand{\O}{\text{O}} % orthogonal group \newcommand{\SU}{\text{SU}} % special unitary group \newcommand{\Spin}{\text{Spin}} % Spin group \newcommand{\RP}{\Rr\mathrm P} % real projective space \newcommand{\CP}{\Cc\mathrm P} % complex projective space \newcommand{\HP}{\Hh\mathrm P} % quaternionic projective space \newcommand{\Top}{\mathrm{Top}} % topological category \newcommand{\PL}{\mathrm{PL}} % piecewise linear category \newcommand{\Cat}{\mathrm{Cat}} % any category \newcommand{\KS}{\text{KS}} % Kirby-Siebenmann class \newcommand{\Hud}{\text{Hud}} % Hudson torus \newcommand{\Ker}{\text{Ker}} % Kernel \newcommand{\underbar}{\underline} %Classifying Spaces for Families of Subgroups \newcommand{\textup}{\text} \newcommand{\sp}{^}(f, \bar f) \colon M \to X$ and $(g, \bar g) \colon N \to Y$$(g, \bar g) \colon N \to Y$ be degree one normal maps of closed smooth manifolds $X$$X$ and $Y$$Y$ with normal invariants $\eta_X(f, \bar f) \in [X, G/O]$$\eta_X(f, \bar f) \in [X, G/O]$ and $\eta_Y(g, \bar g) \in [Y, G/O]$$\eta_Y(g, \bar g) \in [Y, G/O]$.

Exercise 0.1.

Determine the normal invariant,

$\displaystyle \eta_{X \times Y}(f \times g, \bar f \times \bar g \colon M \times N \to X \times Y) \in [X \times Y, G/O],$ $$\displaystyle \eta_{X \times Y}(f \times g, \bar f \times \bar g \colon M \times N \to X \times Y) \in [X \times Y, G/O],$$

in terms of $\eta_X(f, \bar f)$$\eta_X(f, \bar f)$ and $\eta_Y(g, \bar g)$$\eta_Y(g, \bar g)$.