check the picture below.
to bisect and angle, means to cut it into two identical twins, namely ∡DGI and ∡IGH are twins.
[tex]\bf x-3=3x-13\implies \stackrel{\textit{subtracting \underline{x}}}{-3=2x-13}\implies \stackrel{\textit{adding 13}}{10=2x}\implies \cfrac{10}{2}=x\implies \boxed{5=x} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \measuredangle DGI=(5)-3\implies \measuredangle DGI = 2=\measuredangle IGH \\\\\\ \measuredangle DGH=2+2\implies \blacktriangleright \measuredangle DGH=4 \blacktriangleleft[/tex]
