$x$ years ago,the sum of the ages of a mother,father,and two children was $y$ years. What will be the sum of their ages after $z$ years?

$A$ railway half ticket costs half the full fare,but the reservation charges are the same on a half ticket as on a full ticket. One reserved first class ticket from station $A$ to $B$ costs $Rs. 2530$. Also,one reserved first class ticket and one reserved first class half ticket from $A$ to $B$ costs $Rs. 3810$. Find the full first class fare from station $A$ to $B$,and also the reservation charges for a ticket (in $Rs.$).

For the linear equation in two variables $3x + 2y = 8$,if the value of $x$ is $-2$,then $y = \dots$

Solve the following pair of equations by the method of cross-multiplication:
$x + 2y + 1 = 0$
$2x - 3y - 12 = 0$

$x$ is larger in two numbers $x$ and $y$. Two times the larger number is $4$ more than five times the smaller number. The equation form of this data is $\ldots \ldots \ldots \ldots$

Solve the following pair of linear equations by the method of substitution: $3x + y + 1 = 0$ and $2x - 3y + 8 = 0$.