\[\boxed{\text{43\ (43).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ 1) - 0,7x + 350 = 0\]
\[0,7x = 350\]
\[x = 500\]
\[y = 0\ \ \ при\ \ \ x = 500.\]
\[2) - 0,7x + 350 > 0\]
\[0,7x < 350\]
\[x < 500\]
\[y > 0\ \ при\ \ \ x < 500.\]
\[3) - 0,7x + 350 < 0\]
\[0,7x > 350\]
\[x > 500\]
\[y < 0\ \ \ при\ \ \ x > 500.\]
\[\textbf{б)}\ 1)\ 30x + 10 = 0\]
\[30x = - 10\]
\[x = - \frac{1}{3}\]
\[2)\ 30x + 10 > 0\]
\[30x > - 10\]
\[x > - \frac{1}{3}\]
\[3)\ 30x + 10 < 0\]
\[30x < - 10\]
\[x < - \frac{1}{3}.\]