Sara answered 8 questions incorrectly. If she answered 5/7 of the questions correctly, how many questions were correct?

Question

Please help and step by step would be appreciated. 

Answer 1

First you need to find out how many questions there were total. We'll use 'a' as the variable for total questions.

We know that Sara got 8 questions wrong and she got 5/7 of the total questions correct. Therefore, 8 (wrong answers) = 2/7 of the total questions. Set up the equations (2/7)a=8 and solve for 'a' by dividing 8 by 2/7 and that number will be the total number of questions which is 28. You then multiply 28 (total number of questions) and 5/7 (ratio of questions Sara answered correctly) and that gives you 20. Sara answered 20 questions correctly.

Here are the equations again:

(2/7)a = 8

a = 28

(5/7) x 28 = b

b = 20