If the lines $x + 2ay + a = 0$,$x + 3by + b = 0$,and $x + 4cy + c = 0$ are concurrent,then $a, b,$ and $c$ are in which of the following?

The value of $k$ for which the lines $7x - 8y + 5 = 0$,$3x - 4y + 5 = 0$ and $4x + 5y + k = 0$ are concurrent is given by

If the lines $ax + by + c = 0$,$bx + cy + a = 0$,and $cx + ay + b = 0$ are concurrent,then:

The points $(3a, 0)$,$(0, 3b)$,and $(a, 2b)$ are:

If the lines $L_1 \equiv x-2y+3=0$,$L_2 \equiv 2x+y+1=0$,and $L_3 \equiv 3x+y+c=0$ are concurrent and $\theta$ is the acute angle between the lines $L_1=0$ and $L_3=0$,then $\tan \theta=$

If $3a + 5b + 6c = 0$,then the family of lines $ax + by + c = 0$ passes through the fixed point: