If $(x, -1)$ is the solution of the linear equation of two variables $3x - y = 7$,then $x = \ldots$

For a pair of equations $2x + 3y = 1$ and $3x - 2y = 8$,in usual notations $a_{1}b_{2} - a_{2}b_{1} = \dots$

$A$ mother tells her son,"Five years ago,$I$ was five times as old as you were. After ten years,$I$ will be two times as old as you will be." Represent this situation as a pair of linear equations in two variables.

The solution set of a pair of equations $x+y-1=0$ and $2x+2y-2=0$ is $\ldots \ldots \ldots \ldots$

Do the following pair of linear equations have no solution? Justify your answer.
$2x + 4y = 3$
$x = 2y$

For a two-digit number,if the sum of its digits is equal to the product of its digits,then the number is .............