Question

A mathematics test has 50 questions. Four points are given for each correct answer and one point is deducted for each incorrect answer. If Khadija scored 70, then the number of questions she answered incorrectly was?​

Answer 1

26

Explanation:

If x is the number of correct answers, and y is the number of incorrect answers, then:

x + y = 50

x (4) + y (-1) = 70

Solve the system of equations using substitution or elimination. Using substitution:

x = 50 − y

(50 − y) (4) + y (-1) = 70

200 − 4y − y = 70

130 = 5y

y = 26

She answered 26 questions incorrectly.