Solve {l}{I/3x-5y+4z=12}{pi/2y-8z=-10}{a=pi/6x-3y+7z}{text{Solvefor}btext{where}}{b=a}

$$\left. \begin{array} { l } { I / 3 x - 5 y + 4 z = 12 }\\ { \pi / 2 y - 8 z = -10 }\\ { a = \pi / 6 x - 3 y + 7 z }\\ { \text{Solve for } b \text{ where} } \\ { b = a } \end{array} \right.$$

Solve for x, y, z

$$\left\{\begin{matrix}x=-\frac{12\left(-\pi b+20b+21\pi -259\right)}{-7\pi I+48I+2\pi ^{2}-40\pi }\text{, }y=-\frac{4\left(4Ib-35I-14\pi \right)}{-7\pi I+48I+2\pi ^{2}-40\pi }\text{, }z=-\frac{\pi Ib-60I-6\pi ^{2}+50\pi }{-7\pi I+48I+2\pi ^{2}-40\pi }\text{, }&a=b\text{ and }I\neq -\frac{2\pi \left(\pi -20\right)}{48-7\pi }\text{ and }I\neq 0\\x=-\frac{6\left(7\pi -48\right)\left(\pi z-20z+25-3\pi \right)}{\pi ^{2}\left(\pi -20\right)}\text{, }y=-\frac{4\left(5-4z\right)}{\pi }\text{, }z\in \mathrm{R}\text{, }&a=-\frac{7\left(37-3\pi \right)}{\pi -20}\text{ and }I=\frac{2\pi \left(\pi -20\right)}{7\pi -48}\text{ and }b=-\frac{7\left(37-3\pi \right)}{\pi -20}\\x=\frac{6\left(\pi b-20b+259-21\pi \right)}{\pi \left(\pi -20\right)}\text{, }y=\frac{28}{\pi -20}\approx -1.660892362\text{, }z=-\frac{25-3\pi }{\pi -20}\approx 0.923884547\text{, }&I=0\text{ and }a=b\end{matrix}\right.$$