Question 1006496
Let the number of correct answers = x & number of incorrect answers = y

Since I attempted 19 questions, then x + y = 19 ......(1)

For x no. of correct answers I get = 4x

Deduction for y no. of incorrect answers = - 2y

Deduction for (40-19) = 21 non-attempted questions = - 21

Adding these three we get my score, i.e., 25.

Hence,   4x - 2y - 21 = 25

     Or, 4x - 2y = 25 +21 = 46

     Or, 2(2x - y) = 46

     Or, 2x - y = 46/2 = 23 ......(2)

Adding equation (1) & (2) we get,

         x + y + 2x - y = 19 +23 = 42

     Or, 3x = 42

     Or,  x = 42/3 = 14

Therefore, I got 14 questions right.