Answer:
Step-by-step explanation:
We will set up an algebraic equation by counting the wrong answers.
Final score is 50% so half of the answers are wrong.
Let the number of question be x
x/2 answers are wrong.
There is 1 wrong answer in the first 10 questions.
Out of the (x-10) questions remaining, 3/10 are correct so 7/10 of them are wrong.
Adding them together, 1+7/10(x-10)=x/2
1+7/10x-7 = x/2
1/5x = 6
x = 30