Goi so em tho la : x(em) (DK:x>0)
so qua bong la : y(qua) (y>0)
Vi moi nguoi 5 qua thi thua 5 qua ta co pt: 5.x+5=y(1)
Vi moi nguoi 6 qua thi 1 nguoi k co nen : (x-1).6=y(2)
Tu (1)(2) ta co het phuong trinh: \(\left\{{}\begin{matrix}5x+5=y\\\left(x-1\right).6=y\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}5x+5=y\\5x+5=\left(x-1\right).6\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}5x+5=y\\x=11\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}x=11\\y=60\end{matrix}\right.\)
Vay co tat ca 11 em tho va 60 qua bong