Answer:
40%
Explanation:
A percentage is basically x/100.
Therefore, if we convert Siobhan's mark into a fraction, we get 4/10. Then, by converting the fraction to fit x/100, we get 40/100 (remember, we must do the same to both the numerator and the denominator, so in this case it's multiply them by 10). Now that we have x, we can fit that into the answer to get 40%.