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katovenus [111]
2 years ago
8

PLEASE HELP WITH THIS MATH SUM

Mathematics
2 answers:
Studentka2010 [4]2 years ago
5 0

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.
Firdavs [7]2 years ago
3 0

Answer:

27 questions correct

Step-by-step 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

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Morgarella [4.7K]

Answers : A and D

Step - by - step explanation :

tip : when finding constant of proportionality it's always Y divided by X

A = what is 22.5 divided by 3 ?  7.5 ( now multiply 7.5 by the next X [ 4 ] )

what is 7.5 x 4 ?  30 ( and since on the graph it also says 30 then you can assume this one has a proportional relationship )

B = what is 12 divided by 3 ?  4 ( now multiply 4 by the next X [ 5 ] )

what is 4 x 5 ?  20 ( and because the graph says 25 then you know it's NOT a proportional relationship )

C = what is 8.5 divided by 2 ?  4.25 ( now multiply 4.25 by the next X [ 5 ] )

what is 4.25 x 5 ?  21.25 ( and because the graph says 22.5 then you know it's NOT a proportional relationship )

D = what is 10 divided by 2 ?  5 ( now multiply 5 by the next X [ 3 ] )

what is 5 x 3 ?  15 ( and since on the graph it also says 15 then you can assume this one has a proportional relationship )

( sorry it took me so long to write this )

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