To determine how many chairs Erin needs to rent for the costs from A-1 Rental and Tonka Tents to be the same, we can set up an equation based on their pricing structures.
The cost from A-1 Rental for \( x \) chairs is given by:
\[ \text{Cost}_{A-1} = 1.61x + 62.53 \]
The cost from Tonka Tents for \( x \) chairs is given by:
\[ \text{Cost}_{Tonka} = 1.86x + 58.78 \]
To find the number of chairs \( x \) where both costs are equal, we set the two equations equal to each other:
\[ 1.61x + 62.53 = 1.86x + 58.78 \]
Now, we can solve for \( x \):
- Subtract \( 1.61x \) from both sides:
\[ 62.53 = 1.86x - 1.61x + 58.78 \]
- Simplify:
\[ 62.53 = 0.25x + 58.78 \]
- Subtract \( 58.78 \) from both sides:
\[ 62.53 - 58.78 = 0.25x \]
\[ 3.75 = 0.25x \]
- Divide both sides by 0.25:
\[ x = \frac{3.75}{0.25} = 15 \]
Thus, Erin needs to rent 15 chairs for the cost of the rentals to be the same.
The correct answer is C. 15.