Answer:
96
Explanation:
Let's assume that the marks needed in the next exam is
. Then if the average becomes 90,

Now we can simply solve for
:
⇒

⇒
[Multiplying both sides by 4]
⇒
[Subtracting 264 from both sides]
⇒

Therefore, you need to score 96 in your next exam to have an average of 90 on the four exams.