\[y = 5x - 20;\ \ \ \ \ \ \ y = 10x - 70\]
\[5x - 20 = 10x - 70\]
\[10x - 5x = - 20 + 70\]
\[5x = 50\]
\[x = 10.\]
\[y = 5 \bullet 10 - 20 = 50 - 20 = 30.\]
\[Ответ:(10;30).\]