Find the Value at the Red Point: Number Line Coordinate Mapping

First we need to consider the numbers on the number line from left to right:

$-3,-1.5,0$

Then, we'll try to find the common denominator.

If we use the add 1.5 each time, it will give us the correct sequence numbers:

$-3+1.5=-1.5$

$-\text{1}.5+1.5=0$

Therefore:

$0+1.5=1.5$