Petrol Price Changes and Quadratic Equations

The price of petrol in July was \(x\) dollars per litre and Mr Lee spent \(\$72\) on petrol.

1. Write down an expression, in terms of \(x\), for the amount of petrol he filled his car with in July.

In August, the price of petrol increased by \(15\) cents per litre.

Mr Lee spent the same amount of money on petrol.

2. Write down an expression, in terms of \(x\), for the amount of petrol he filled his car with in August.

Mr Lee noticed that he was getting \(2\) litres of petrol less in August than in July.

3. Form an equation in \(x\) and show that it reduced to \(20{{x}^{2}}+3x-108=0\).
4. Solve the equation \(20{{x}^{2}}+3x-108=0\).
5. Hence, find the price of petrol in August.