Alex thinks of a number.
He then does the following operations:
Multiply by 2, subtract 3, multiply by 2 then add 34 (in that order).
He finds that the number he ends up with is 8 times his original number.
What was Alex's original number?
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This question is best answered by forming an algebraic equation then solving it. Let Alex's original number be x.
First operation gives 2x
Second operation gives 2x- 3
Third operation gives 2(2x- 3)
Fourth operation gives 2(2x- 3) + 34
This is equal to 8 times the original number
2(2x - 3) + 34 = 8x
4x- 6 + 34 = 8x
x = 7
Alex's original number was 7.
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