Çözüldü Problem Solving Using a One-Variable Equation

In a 100-question exam, 4 points are awarded for each correct answer, and 1 point is deducted for each incorrect answer. If a student scores 185 points without leaving any questions blank, how many questions did she or he answer correctly?

A) 45
B) 48
C) 54
D) 57
E) 60

Number of correct answers out of 100 questions: x
Number of wrong answers: 100 - x
Total points earned for correct answers: 4x
Total points deducted for incorrect answers: (100 - x)·1 = 100 - x
Total net points earned: 4x - (100 - x) = 185 ⇒ 5x = 285 ⇒ x = 285 / 5 = 57.

Source (Turkish): Final Mathematics - 1 with Subject Explanations, Page 105, Example 10