Your difference between the input max and input min is:
-22840 -(-25383) = 2903
So if we want to know the value at 4, calculated as follows:
5/2903 = 4/x
4 * 2903 / 5 = x
2322.4 = x
Now we add this to the base at 0 which is -25383
So the value of 4 will give -25383 + 2322.4 = -23060.6
Regards,