Question

X+y=10 , x+z=20 , y+z=24, x+y+z=???
and why??

Answer 1

`+\left\{\begin{array}{ccc}x+y=10\\x+z=20\\y+z=24\end{array}\right\ \ \ \ \ add\ both\ sides\\----------\\2x+2y+2x=54\ \ \ \ |divide\ both\ sides\ by\ 2\\\\x+y+z=27`