SATMathematics Practice Test 1

To determine the number of salads sold, write and solve a system of two equations. Let x equal the number of salads sold and let y equal the number of drinks sold. Since the number of salads plus the number of drinks sold equals 209, the equation $\mathit{x}+\mathit{y}=209$ must hold. Since each salad cost $6.50$, each soda cost 2.00, and the total revenue was $\mathrm{\$}836.50$, the equation $6.50\mathit{x}+2.00\mathit{y}=836.50$ must also hold. The equation x + y = 209 is equivalent to 2x + 2y = 418, and subtracting each side of $2\mathit{x}+2\mathit{y}=418$ from the respective side of $6.50\mathit{x}+2.00\mathit{y}=836.50$ gives $4.5\mathit{x}=418.50.$ Therefore, the number of salads sold, x, was $\mathit{x}=\frac{418.50}{4.50}=93.$
Choices A, C, and D are incorrect and could result from errors in writing the equations and solving the system of equations. For example, choice C could have been obtained by dividing the total revenue, $\mathrm{\$}836.50$, by the total price of a salad and a soda, $\mathrm{\$}8.50$, and then rounding up.