Question

Weiling took part in a Mathematics quiz which consist of 60 questions. For every correct answer, 3 marks would be awarded. For every wrong answer, 2 marks would be deducted. Weiling answered all the questions and scored a totał of 140 marks for the quiz. How many questions did she answer correctiy?

Answer 1

Right answer = 52

Wrong answers = 8

Explanation:

Every correct answer = + 3

Every wrong answer = - 2

Number of correct answers = x

Number of wrong answers = y

x + y = 60 - - - (1)

3x - 2y = 140 - - - (2)

From (1) :

x = 60 - y

Put x = 60 - y into (2)

3(60 - y) - 2y = 140

180 - 3y - 2y = 140

180 - 5y = 140

-5y = 140 - 180

-5y = - 40

y = 8

x = 60 - y

x = 60 - 8

x = 52

Right answer = 52

Wrong answers = 8