The pair of equations $2x + 6y = 10$ and $3x + 9y - 15 = 0$ has..........

In a competitive examination,one mark is awarded for each correct answer while $\frac{1}{2}$ mark is deducted for every wrong answer. Jayanti answered $120$ questions and got $90$ marks. How many questions did she answer correctly?

The graph of a pair of lines $3x - 2y = 2$ and $6x - 4y = 4$ is.........

$x=-1$ and $y=-2$ is one of the solutions of the equation $\ldots \ldots \ldots \ldots$

Comparing the equation $x=4$ with the standard form $ax+by+c=0$,we get $b=\ldots \ldots \ldots$

If the sum and the difference of the digit at the ten's place and the digit at the unit's place of a two-digit number are the same,then the digit at the unit's place is ...........