Jordan drives to the store at 30 miles per hour. On her way home, she averages only 20 miles per hour. If the total driving time takes half an hour, how far does she live from the store?

Fill out the Rate column in the table below.

[tex]\[
\begin{array}{l}
a = 30 \\
b = 20
\end{array}
\][/tex]

\begin{tabular}{|c|c|c|c|}
\hline & Distance & Rate & Time \\
\hline To store & & [tex]$a$[/tex] & \\
\hline \begin{tabular}{l} Return \\ home \end{tabular} & & [tex]$b$[/tex] & \\
\hline
\end{tabular}



Answer :

Let's solve the problem step-by-step.

1. Identify Rates:
- Jorden drives to the store at a rate of [tex]\( 30 \)[/tex] miles per hour.
- Jorden drives back home at a rate of [tex]\( 20 \)[/tex] miles per hour.

2. Total Time:
- The total driving time (to the store and back home) is [tex]\( 0.5 \)[/tex] hours.

3. Time Calculation:
- We need to calculate the time needed for each leg of the trip using the distance and rates.

4. Distance Calculation:
- Let [tex]\( d \)[/tex] be the distance (in miles) from Jorden's home to the store.
- Time for the trip to the store is [tex]\( \frac{d}{30} \)[/tex] hours.
- Time for the return trip home is [tex]\( \frac{d}{20} \)[/tex] hours.
- According to the problem, the total time is the sum of the times for both legs of the trip:
[tex]\[ \frac{d}{30} + \frac{d}{20} = 0.5 \][/tex]

5. Solve for Distance:
- Combine the fractions:
[tex]\[ \frac{d}{30} + \frac{d}{20} = 0.5 \][/tex]
- Find a common denominator (which is [tex]\( 60 \)[/tex]):
[tex]\[ \frac{2d}{60} + \frac{3d}{60} = 0.5 \][/tex]
[tex]\[ \frac{5d}{60} = 0.5 \][/tex]
- Simplify the equation:
[tex]\[ \frac{d}{12} = 0.5 \][/tex]
- Multiply both sides by [tex]\( 12 \)[/tex] to solve for [tex]\( d \)[/tex]:
[tex]\[ d = 0.5 \times 12 = 6 \text{ miles} \][/tex]

Given these calculations, the table can be filled as follows:

[tex]\[ \begin{array}{c} a=30 \\ b=20 \end{array} \][/tex]

\begin{tabular}{|c|c|c|c|}
\hline & Distance & Rate & Time \\
\hline To store & 3 & 30 & \\
\hline \begin{tabular}{l}
Return \\
home
\end{tabular} & 2 & 20 & \\
\hline
\end{tabular}

The value next to the letter a is 30, and the value next to the letter b is 20. The distance to the store is [tex]\( 6 \)[/tex] miles.