Cómo fue cambiando el modo de vida de los primeros pobladores a partir de la agricultura?

we have to find the value of the x°=<GHC

In the triangle BDH,

<D=31°

<B=47°

we know that,

Sum of three angle of a triangle is 180°

According to the question,

<D+<B+<BHD=180°

31°+47°+<BHD=180°

78°+<BHD=180°

<BHD=180°-78°

<BHD=102°

But,

<GHC and <BHD forms a straight line

so,

<GHC+<BHD=180°

102°+x=180°

x=180°-102°

x=78°

Therefore,

The value of x is 78°