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}
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\rule{34em}{0.25pt}\\\\
\measuredangle DGI=(5)-3\implies \measuredangle DGI = 2=\measuredangle IGH
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\measuredangle DGH=2+2\implies \blacktriangleright \measuredangle DGH=4 \blacktriangleleft[/tex]
