The cost of petrol rises by #2.55 a liter. Last week , a driver bought 20 litres at the old price this week he bought 10 litres at the new price altogether, the petrol cost not less than #312.50.what is the range of the old price for a liter of petrol

Answer 1

Let x be the old price of petrol per liter.

Last week, the driver bought 20 liters at the old price, so the cost would be 20x.

This week, the driver bought 10 liters at the new price, which is x + 2.55, so the cost would be 10(x + 2.55).

The total cost of petrol is not less than #312.50, so we can write the equation:

20x + 10(x + 2.55) ≥ 312.50
20x + 10x + 25.5 ≥ 312.50
30x + 25.5 ≥ 312.50
30x ≥ 287

Dividing by 30 on both sides, we get:

x ≥ 9.57

Therefore, the range of the old price for a liter of petrol is x ≥ #9.57.