Algebraic Expressions, Identities and Formulae

Kenneth's monthly bill for his mobile usage is shown in the table below.

1. The total amount of his bill including \(8\%\) GST is \(\$135.54\). Calculate the amount of other usage he has incurred.

   [3]

2. The table below shows the different mobile plans that is available from the service provider that Kenneth has subscribed with.

   Plan	Plan 1	Plan 2
   Free Item	30 GB Data \\ 300 mins outgoing \\ 300 SMS	60 GB Data \\ 600 mins outgoing\\600 SMS
   Cost	\(\$68\)	\(\$88\)
   \(\$5.35\) for every additional \(1\text{ GB}\). \(\$1\) for every additional \(10\) minutes outgoing or part thereof \(\$1\) for every additional \(10\) SMS or part thereof

Kenneth currently uses Plan 2 and his usage per month is as follows:

• \(33\text{ GB}\) Data

• \(305\) mins outgoing calls

• \(15\) SMS

Should Kenneth change to Plan \(1\) for a cheaper monthly bill?[3]