Audrey thinks of a number.
She then does the following operations:
Multiply by 3, subtract 7, multiply by 2 then add 26 (in that order).
She finds that the number she ends up with is 9 times her original number.
What was Audrey's original number?
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This question is best answered by forming an algebraic equation then solving it. Let Audrey's original number be x.
First operation gives 3x
Second operation gives 3x- 7
Third operation gives 2(3x- 7)
Fourth operation gives 2(3x- 7) + 26
This is equal to 9 times the original number
2(3x - 7) + 26 = 9x
6x- 14 + 26 = 9x
x = 4
Audrey's original number was 4.
Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.
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