I have 40 questions, 4 marks given for a correct answer, 2 marks deducted for each wrong answer and 1 mark deducted for for each answer not attempted I attempt 19 and score 25 marks.how many questions did I get right

Answer 1

Let x be the no. of questions I got right and y be the no. of question I got wrong.
So,
x+y=40........(1)
&
4x-2y-21=25
4x-2y=46
2x-y=23........(2)
comparing equations (1) and (2)
3x=63
x=21......(3)
putting the value of equation (3) in equation (1)
21+y=40
y=19
So, 21 questions I got right

Answer 2

No. of Attempt question =19
No. Of unattemt question=21

No. Of right question = x

No. Of wrong question =19-x

From question ,

4x-(19-x)2- 21=25
On solving
X= 14