10x+10y=750=>8x+8y=600(1) mà 11,75x + 8y =750
=>3,75x =150 =>x=40
thay x=40 vào (1) ta có 8*40+8y=600=>y=35
\(\left\{{}\begin{matrix}10x+10y=750\\11,75+8y=750\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x+y=750:10\\8y=750-11,75\end{matrix}\right.\\ \)
\(\Leftrightarrow\left\{{}\begin{matrix}x=75-y\\8y=738,25\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=-17,28125\\y=92,28125\end{matrix}\right.\)