Đáp án:
Giải thích các bước giải:
Có: s=v.t
\(\begin{array}{l}
\to \left\{ \begin{array}{l}
xy = \left( {x - 10} \right)\left( {y + \frac{3}{4}} \right)\\
xy = \left( {x + 10} \right)\left( {y - \frac{1}{2}} \right)
\end{array} \right.\\
\to \left\{ \begin{array}{l}
xy = xy + \frac{{3x}}{4} - 10y - \frac{{15}}{2}\\
xy = xy - \frac{x}{2} + 10y - 5
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\frac{{3x}}{4} - 10y = \frac{{15}}{2}\\
- \frac{x}{2} + 10y = 5
\end{array} \right. \to \left\{ \begin{array}{l}
3x - 40y = 30\\
- x + 20y = 10
\end{array} \right.
\end{array}\)
