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Write-up


Title.
Double Trouble

Problem Statement
What number can you add to 129 and subtract from 129 such that the sum of the number and 129 is twice the difference between 129 and the number?

Problem setup

Restate the problem in your own words. Discuss mathematical similarities between this problem and other problems you have solved.

 

Plans to Solve/Investigate the Problem

Create an equation based on the way the problem is written (order of stipulations) and a spreadsheet to support/solve the problem. 

 

Investigation/Exploration of the Problem

Equation where n=number

n+129= 2(129-n)

n+129=258-2n

3n=129

n=43

 

Double Trouble

 

 

 

 

N

N+129

129-N

2(129-N)

50

179

79

158

49

178

80

160

48

177

81

162

47

176

82

164

46

175

83

166

45

174

84

168

44

173

85

170

43

172

86

172

 

 

Extensions of the Problem
The problem can be further explored by writing the equation as follows:

n+129=2(n-129)

n+129=2n-258

387=n

387+129=2(387-129)

516=2(258)

516=516

Discussion and examination of the order of stipulations will eliminate this equation as a possibility (add to and subtract from).

Author & Contact
Susan Kelly
mailto:skelly@rockdale.k12.ga.us

Link(s) to resources, references, lesson plans, and/or other materials
Link 1
Link 2

 

 

 

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