Answer:
4 questions
Step-by-step explanation:
90% is the same as multiplying a number by 0.9. Let's say the number of questions on the quiz is x. This means the amount she got right was 0.9x. We are given this is 36, so we can set them equal and simplify:
0.9x = 36
x = 40
She must have gotten 40 - 36, or 4 questions wrong.
