Question

In 2004, approximately 5 million cars and trucks were classified as flex-fuel, which means they could run on gasoline or ethanol. In 2006, that number increased to 7.5 million.

How many more cars and trucks were flex-fuel in 2006?

Short answer

The number of more flex-fuel cars and trucks in 2006 is 2.5 million.

Step-by-step solution

Step 1. Given information.

The number of more flex-fuel cars and trucks in 2006 = 7.5 million.

The number of more flex-fuel cars and trucks in 2004 = 5 million.

Step 2. Introduce the variable.

Consider the number of more flex-fuel cars and trucks in 2006 be x.

Step 3. Write the equation.

Since, in 2006, the number is increased to 7.5 million from 5 million.

Therefore,

$x+5=7.5$

Step 4. Solve the equation.

Take the equation $x+5=7.5$.

Subtract 5 from both sides of the equation.

$$\begin{gathered} x+5-5=7.5-5 \\ x=7.5-5 \end{gathered}$$

So,

$x=2.5$million