When thrice of x is added to 7, we get 13, then the value of x is :

In an examination which had 200 questions, students score 4 marks for every correct answer and lose 1 mark for every wrong answer.

A student attempted all the 200 questions and scored 200 marks. The number of questions, student answered correctly in the examination, is:

The graphs of ax+by = c and dx+ey = f will be:

(A) parallel, if the system has no solution.

(B) coincident, if the system has finite numbers of solutions.

(C) intersecting, if the system has only one solution.

Which of the above statements is/ are correct?

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:

The sum of digits of a two-digit number is 14 and the difference between the two digits of the number is 2. The product of the two digits of the number is:

For what value of k, the system of equations $3x - ky - 3 = 0$ and $2x - 3y - 4 = 0$ has no solution?

For what value of k, the system of equations $kx + 4y - k + 4 = 0$ and $16x + ky = k$ has an infinite number of solutions?