In a 2-digit number, the ten's digit is two times its unit's digit and the number is 12 less than two times the number obtained by interchanging its digits. Find the original number.

Reena is twice as old as Sunita. Three years ago, Reena was three times as old as Sunita. What is present age of Reena?

Five years ago, Sanjana was thrice as old as Sanjay. Ten years later, Sanjana will be twice as old as Sanjay. The age of Sanjay and Sanjana are respectively

A. 20

B. 30

C. 40

D. 50

Choose the correct answer from the options given below:

Which one of the following pairs of linear equations has/ have infinite many solutions?

(A) $9x + 3y + 12 = 0$, and $18x + 6y + 24 = 0$

(B) $2x - 3y = 13$, and $7x - 2y = 20$

(C) $x + y = 5$, $2x + 2y = 10$

(D) $3x + y - 3 = 0$ and $2x + \frac{2}{3}y = 2$

Choose the correct answer from the options given below:

If $6x - 10y = 10$ and $\frac{x}{x+y} = \frac{5}{7}$, then (x-y) is equal to:

System of linear equations 2x + 4y +1 = 0 and 4x + 8y + 2 = 0 has/ have :

In the following system of linear equations $7x - 15y = 2$ and $x + 2y = 3$, the value of x and y is: