The sum of internal angles of a triangle is 180 degrees.
6.
The sum of the internal angles is,
[tex]\begin{gathered} 5x+3x+12x=180 \\ 20x=180 \\ x=\frac{180}{20} \\ x=9 \end{gathered}[/tex]
Thus, the value of x is 9 for the triangle LKJ.
7.
The sum of the internal angles of the triangle STR is 180 degrees.
[tex]\begin{gathered} (2x+6)+(2x-2)+(x+16)=180 \\ 5x+20=180 \\ 5x=180-20 \\ x=\frac{180-20}{5} \\ x=32 \end{gathered}[/tex]
Thus, the value of x is 32 for the triangle STR.
8.
For triangle WXY,
[tex]\begin{gathered} (3x-2)+(4x-18)+(x)=180 \\ 8x-20=180 \\ 8x=180+20 \\ x=\frac{180+20}{8} \\ x=25 \end{gathered}[/tex]
Thus, the valu of x is 25 for triangle WXY.
