Rachel thinks of a number.
She then does the following operations:
Multiply by 2, subtract 5, multiply by 3 then add 45 (in that order).
She finds that the number she ends up with is 12 times her original number.
What was Rachel's original number?
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This question is best answered by forming an algebraic equation then solving it. Let Rachel's original number be x.
First operation gives 2x
Second operation gives 2x 5
Third operation gives 3(2x 5)
Fourth operation gives 3(2x 5) + 45
This is equal to 12 times the original number
3(2x  5) + 45 = 12x
6x 15 + 45 = 12x
...
x = 5
Rachel's original number was 5.
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