1. Check it out! 1.5.1: Rearranging Formulas 1

2. Read the scenario below. Write an equation and use it to answer the questions that follow. In January 2011, the national average for 5 gallons of gasoline was $17.20. 1.What was the national average for 1 gallon of gas? 2.What was the price for 18 gallons of gas? 2

3. 1.What was the national average for 1 gallon of gas? Set up the equation. Let x represent the cost per gallon of gasoline. 5x = 17.20 Using inverse operations, solve this equation for x. 5x = 17.20Original equation Divide each side by 5. x = 3.44 Interpret the solution. The average cost of 1 gallon of gasoline was $3.44. 3 1.5.1: Rearranging Formulas

4. 2.What was the price for 18 gallons of gas? To find the cost of 18 gallons of gasoline, multiply the number of gallons by the cost per gallon. 18 3.44 = $61.92 Interpret the solution. The cost of 18 gallons of gasoline at $3.44 a gallon is $61.92. 4 1.5.1: Rearranging Formulas