at a gas station mr. Carrington brought 12.8 gallons of gas priced at $2.85 per gallon. how much did this purchase cost?

The method is the unitary method.

We know the price of 1 unit of a commodity.

We multiply it by the units purchased to get the total cost.

Here the price of each gallon of gas is $2.85

Mr Carrington purchased 12.8 gallons of gas.

Multiplying the quantity with the unit price, we get

The total amount = 12.8 * 2.85 = $36.48

The purchase of 12.8 gallons of gas shall cost $36.48.