For the linear equation in two variables $2x - 5y = 3$,if $y = -1$,then $x = \ldots$

The sum of the present age of a father and twice the present age of a son is $70$ years. Also,the sum of twice the present age of father and the present age of son is $95$ years. Find their present ages.

Solve the following pair of linear equations by the method of substitution: $2x - 3y = -11$ and $4x - 6y + 22 = 0$.

The sum of the digits of a two-digit number is $6$. If the digit at the unit's place is twice the digit at the ten's place,then that number is..........

Solve the following pair of linear equations by the substitution method.
$x+y=14$
$x-y=4$

Solve the following pair of linear equations by the method of substitution: $x + y = 7$ and $5x + 12y = 7$.