Find the Missing Number: Grid Point Value at Red Marker

First let's look at the numbers on the axis from left to right:

$90,30,10$

Now we can try to find the common denominator.

Note that if we divide 90 by 3, then we get 30.

If we divide 30 by 3, then we get 10.

Therefore, if we divide 10 by 3, then we will get our answer:

$\frac{10}{3}$