Question

The score on a trivia game is obtained by subtracting the number of incorrect answers from twice the number of correct answers. If a player answered 40 questions and obtained a score of 50, how many questions did the player answer correctly?

Answer 1

the player answered 30 questions correctly. 30x2=60 and 60-10= 50

Answer 2

Answer: the player has 30 correct answers.

Explanation: If the number of correct answers is C, and the number of incorrect answers is I, the score in the game is obtained by:

S = 2*C - I

two times the number of correct answer minus the number of incorrect answers

We know that S = 50 and that the player answered 40 questions:

So we have that:

I + C = 40

here we have a system of equations and 2 variables:

First, we can write C = 40 - I, and replace it in the first equation:

S = 50 = 2*C - I= 2*(40 - I) - I = 80 - 3I

50 = 80 - 3I

3I = 80 - 50 = 30

I = 30/3 = 10

so the player answered 10 questions wrong.

and we know that I + C = 40

so we can replace I by 10 and get:

10 + C = 40

C = 40 - 10 = 30

And find that the player has 30 correct answers and 10 incorrect answers.