Final answer:
Mia scored 45% and her mark out of 40 is 18.
Step-by-step explanation:
To find Mia's mark out of 40, you can set up a proportion:
Percentage score / 100 = Mark / Total marks
Plugging in the given values:
45 / 100 = x / 40
Cross multiplying, we get: 45 * 40 = 100 * x
This simplifies to: 1800 = 100 * x
Dividing both sides by 100, we get: x = 18
Therefore, Mia's mark out of 40 is 18.