Mathematics

Jenna Willis

26 August, 17:50

Analyze Mr Johnson's work and identify his

mistake.

Mr Johnson is also comparing the two mobile

phone data plans. Talk First charges $20 plus $5

per GB of data, while Mobile Plus charges $30

plus $3 per GB of data At what amount of GB use

will the cost of the two data plans be the same?

Mr Johnson wrote this equation for the scenario

1. d = amount of data used (GB)

2. Talk First Mobile Plus

3. 20d+5=30d+3

In step 1 his variable should be c

representing company

In step 2 his translated equation should be

Talk First + Mobile Plus = Total

Money

In step 3 he multiplied the variable by the

base monthly cost nstead of by the

cost per GB