Question 972966
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PART 1: QUIZ
C=correct answers; W=wrong answers
C+W=20
W=20-C Use this to substitute for W.
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3C-2W=0 Substitute for W.
3C-2(20-C)=0
3C-40+2C=0
5C=40
C=8 Jay answered 8 questions correctly.
CHECK:
W=20-C=20-8=12 Jay answered 12 questions incorrectly.
3C-12W=0
3(8)-2(12)=0
24-24=0
0=0
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PART 2:CARDS
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H=number of Henry's cards; G=number of Gordon's cards=3H;
I=number of Ivan's cards=2G=6H
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H+G+I=90 Substitute for G and I
H+3H+6H=90
10H=90 
H=9 Henry had 9 cards.
I=6H=6(9)=54 Ivan had 54 cards.
G=3H=3(9)=27
CHECK:
H+G+I=90
9+27+54=90
90=90
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I-H=54-9=45 
ANSWER: Ivan had 45 more cards than Henry.