SAT Mathematics Practice Test 7

Let x represent the number of correct answers from the player and y represent the number of incorrect answers from the player. Since the player answered 40 questions in total, t he equation x + y = 40 represents this situation. Also, since the score is found by subtracting the number of incorrect answers from twice the number of correct answers and the player received a score of 50, the equation 2x – y = 50 represents this situation. Adding the system of two equations together yields (x + y) + (2x – y) = 40 + 50. This can be rewritten as 3x = 90. Finally, solving for x by dividing both sides of the equation by 3 yields x = 30.