Question

The cost of petrol rises by 2 cents a liter. last week a man bought 20 liters at the old price. This week he bought 10 liters at the new price. Altogether, the petrol costs $9.20. What was the old price for 1 liter?

Answer 1

Suppose the old price per liter, in dollars per liter, is x.

The new price is 2 cents more, so the new price is x + 0.02.

He bought 20 liters at the old price and 10 at the new price, for a total of $9.20

Setting up the appropriate equation: 20(x) + 10(x + 0.02) = 9.20
Solve for x