Question

PLEASE HELP WITH THIS MATH SUM

David answered 60 questions in a test. For every correct answer, he received 4 marks. For
every incorrect answer, 7 marks were deducted from his final score. He scored 108 marks.
How many questions did David answer correctly?

Answer 1

How many questions did David answer correctly? David answered 48 questions correctly.

We’ll call the number of correct answers a, incorrect answers b.
60 questions on the test gives us:
a + b = 60
And the scoring gives us:
4a - 7b = 108

First we’ll solve for a in terms of b:
a = 60 - b
The we’ll substitute that value for a in the second equation to get a numerical value for b:

4(60 - b) - 7b = 108
240 - 4b - 7b = 108
-11b = -132
b = 12

Now we go back to the first equation and get a numerical value for a:
a = 60 -b
a = 60 - 12
a = 48

Check the math with the scoring equation:
4(48) - 7(12) =
192 - 84 = 108

Please lmk if you have any questions.

Answer 2

27 questions correct

Explanation:

Well 108 marks and 4 marks for each correct,techinally you can’t subtract since 108 is the final score, and the thing was already subtracted so \divide.

108/4= 27

27 correct answers