What is the equation of the line passing through $(3, -4)$ and $(4, 3)$?

$A$ line $L$ intersects the lines $3x - 2y - 1 = 0$ and $x + 2y + 1 = 0$ at the points $A$ and $B$. If the point $(1, 2)$ bisects the line segment $AB$ and $\frac{x}{a} + \frac{y}{b} = 1$ is the equation of the line $L$,then $a + 2b + 1 = $

The equation of the line passing through $(1, 2)$ and perpendicular to $3x + 4y + 5 = 0$ is

The equation of the line parallel to $x/a + y/b = 1$ and passing through $(a, b)$ is .....

If $x \cos \theta + y \sin \theta = p$ is the normal form and $y = mx + c$ is the slope-intercept form of the line $x + 2y + 1 = 0$,then $\tan^{-1}(\tan \theta + m + c) = $

If three points $(h, 0), (a, b),$ and $(0, k)$ lie on a line,show that $\frac{a}{h} + \frac{b}{k} = 1$.