Question

Dominic is driving on a long road trip. He currently has 10 gallons of gas in hiscar. Each hour that he drives, his car uses up 1.25 gallons of gas. Write anequation to represent the scenario. How much gas will Dominic have in 3hours?

Answer 1

Dominic is driving on a long road trip. He currently has 10 gallons of gas in his

car. Each hour that he drives, his car uses up 1.25 gallons of gas. Write an

equation to represent the scenario. How much gas will Dominic have in 3

hours?

Step 1

Let

Dominic has 10 gallons of gas

. Each hour that he drives, his car uses up 1.25 gallons of gas, here we have a relation between the time and the gas the car uses

`\text{1 hour}\Rightarrow1.25\text{ gallons of gas}`

Write an

equation to represent the scenario

Step 2

use a rule of three

Let

y, the gas the car uses

x, the time Dominic drives

`\begin{gathered} \text{if } \\ 1\Rightarrow1.25 \\ \text{then} \\ x\Rightarrow y \\ \end{gathered}`

the relation is

`\begin{gathered} (1)/(1.25)=(x)/(y) \\ \text{solve for y} \\ y=1.25\cdot x\text{ EQUATION} \end{gathered}`

Step 2

How much gas will Dominic have in 3

hours?

find y when x=3, this is the gas use

`\begin{gathered} y=1.25\cdot x \\ y=1.25(3) \\ y=3.75 \end{gathered}`

Step 3

the gas Dominic has is

`\begin{gathered} \text{gas = initial -used} \\ \text{gas}=10-3.75 \\ \text{gas}=6.25 \end{gathered}`

Then, after 3 hours Dominic has 6.25 gallons