Let:
- \( A \) be the total cost of rental car A after \( x \) days.
- \( B \) be the total cost of rental car B after \( x \) days.
The costs can be defined as:
- For rental car A: \( A = 100 + 10x \)
- For rental car B: \( B = 50 + 20x \)
To find out when the prices are equal, we set the two equations equal to each other:
\[ 100 + 10x = 50 + 20x \]
Now, we solve for \( x \):
- Subtract \( 10x \) from both sides:
\[ 100 = 50 + 10x \]
- Subtract 50 from both sides:
\[ 50 = 10x \]
- Divide by 10:
\[ x = 5 \]
So the solution is \( x = 5 \), which means after 5 days, the prices of rental car A and rental car B are equal.
Interpretation
The conclusion is that after 5 days of rental, the total cost of both rental car A and rental car B will be the same.