eQuation

A Maths Starter of The Day

Jamie thinks of a number which he types into his calculator.

He then does the following operations:

Multiply by 4, subtract 5, multiply by 2 then add 5 (in that order).

He finds that the number he ends up with is 7 times his original number.

What was Jamie's original number?

 

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Keywords: Starter | Algebra

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Answer

This question is best answered by forming an algebraic equation then solving it. Let Jamie's original number be x.

First operation gives 4x

Second operation gives 4x - 5

Third operation gives 2(4x - 5)

Fourth operation gives 2(4x - 5) + 5

This is equal to seven times the original number

2(4x - 5) + 5 = 7x

8x - 10 + 5 = 7x

8x = 7x + 5

x  = 5

Jamie's original number was 5.


Teacher, do your students have one to one access to computers?

Whether your students each have a TabletPC or share a desktop PC, this activity lends itself to eLearning (Engaged Learning).

Here's the URL which will take students to our eQuation Generator which provides unlimited practice solving linear equations.

http://www.transum.org/go/?to=eQuation