Zachary is helping his younger brother, Sterling, learn his

I couldn't get how you got to Eqn (1). Bit light on that?

If he would have answered 12 Q correctly. he would have had 12 x 3 = 36 candies
1 wrong 11 right .. Num of candies 11 x 3 - 1 x 2 = 31

Question says if he would have answers 2 more correctly the number of candies he would have is 31
The number of answer given correct so far 11 - 2 = 9

1. Let x be the number of questions answered correctly and y be the number of questions answered wrongly
2. 12 questions are answered. Since x questions are answered correctly, two more questions answered correctly would mean x+2 questions answered correctly and y-2 questions answered incorrectly.
3. 3(x+2) - 2(y-2)=31 or 3x -2y=21
4. Also, x+ y = 12
5, Solving (3) and (4) we get, x= 9 or the number of questions answered correctly so far is 9.

[quote="akshayb2"]Zachary is helping his younger brother, Sterling, learn his multiplication tables. For every question that Sterling answers correctly, Zachary gives him 3 pieces of candy. For every question that Sterling answers incorrectly, Zachary takes away two pieces of candy. After 12 questions, if Sterling had answered 2 more questions correctly, he would have earned 31 pieces of candy. How many of the 12 questions did Zachary answer correctly?

A. 6
B. 7
C. 8
D. 9
E. 10

Solution:
let "r" be the number of right questions and "w" be number of wrong questions.
so, after 12 questions, he does 2 correct and scores 31 in total.

12q + 2(3)=31 : 3 is score for correct answer
12q=25
getting to eqution:
3r-2w = 25 (3 and 2 denote, scores of right and wrong)
3 ( ) -2 ( ) =25 : check values from answer choice. none but 9 satisfies.
3( 9 ) - 2(1) =25
so, "D"

checking with options in this question took just 20 sec .i think this is best approach for this question.

I did the same way. Can someone explain what's wrong with this method, please? Thanks in advance!

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