4. Your car is down to \( 1 / 8 \) of a tank of petrol. It has a 60 litre tank. a) How much petrol is in it? b) What fraction of the tank will you have to put in it? c) How many litres is that? d) If fuel is \( \$ 1.61 \) per litre, how much will it cost to fill?

To determine how much petrol is in your car, we start with the total tank capacity of 60 litres. Since your car is down to \( \frac{1}{8} \) of a tank, you simply multiply \( 60 \times \frac{1}{8} = 7.5 \) litres. Next, to find out what fraction of the tank you need to fill it back up, you would subtract the amount already in the tank from the full capacity: \( 60 - 7.5 = 52.5 \) litres. The fraction of the tank you need to fill is \( \frac{52.5}{60} = \frac{7}{8} \). In terms of litres, you need to put in 52.5 litres to fill the tank back to full. Finally, if fuel costs \( \$ 1.61 \) per litre, you’d multiply the litres needed by the price: \( 52.5 \times 1.61 = 84.525 \). So, it will cost you approximately \$ 84.53 to fill your tank.