SOLUTION: In a test, all questions were of equal value of 1 mark. If you answered 9 of the first 10 questions correctly, but only 3/10 of the remaining questions correctly, you would have sc

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Question 1041108: In a test, all questions were of equal value of 1 mark. If you answered 9 of the first 10 questions correctly, but only 3/10 of the remaining questions correctly, you would have scored 50% for the whole test. If let x be the number of questions in the test, make an equation and find x.
I'm not sure how to make the equation, please help. I found that the score of the remaining questions is 3/10 (x-10).
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
There are X questions on the test.
Of the first ten, you answer 9 correctly.
That leaves X-10 questions left on the test since,
10%2BX-10=X
So then scoring (3/10) of the remaining gives you,
%283%2F10%29%28X-10%29 additional correct answers.
So the total number of correct answers is,
9%2B%283%2F10%29%28X-10%29
and that equals 50% of all of the questions, X.
9%2B%283%2F10%29%28X-10%29=%2850%2F100%29X
Multiply both sides by 10.
90%2B3%28X-10%29=5X
90%2B3X-30=5X
2X=60
X=30