Solve the following pair of linear equations by the method of elimination: $2x + 5y = 7$ and $4x + 10y = 12$.

Which of the following groups matches the data of Part $I$ with the data of Part $II$?

Part $I$	Part $II$
$1. x+2y=3, 2x+4y=5$	$a. \text{Solution set is a singleton set.}$
$2. 2x+3y=6, x+\frac{3}{2}y=3$	$b. \text{Solution set is an empty set.}$
$3. 3x-y=0, x-y+6=0$	$c. \text{Solution set is an infinite set.}$
	$d. \text{Solution set contains two members.}$

Naresh has double the money that Yogesh has. If Naresh gives Yogesh ₹ $20$,then both have equal money. The pair of equations obtained from this data is $\ldots \ldots \ldots \ldots .$

Five years ago,the sum of the ages of a father and two sons was $x$ years. Then,after five years,the sum of the ages of all will be $\ldots \ldots \ldots$ years.

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

Aruna has only $Rs. 1$ and $Rs. 2$ coins with her. If the total number of coins that she has is $50$ and the amount of money with her is $Rs. 75$,then the number of $Rs. 1$ and $Rs. 2$ coins are,respectively