Calculate Figure Based off 3 Values : Complex Formula?

Good morning!

I'm trying to create a formula using 3 values. All of the values are between 1 and 100. For the purposes of this we'll call the values E, I and A and the value we want to calculate C. I'm trying to write a "simple" formula to do this, but I'm struggling a bit. The logic for the result is:

C= (Ix8)+(Ax4)
C= round (C/4)

If (C<250) then C=round ((C/250)x100)
If (C>250) then C=round ((250/C)x100)
If (C=250) then C= 100

If (E<11) then C=round (C-(C/10))
If (E<21) then C=round (C-(C/10))
If (E<31) then C=round (C-(C/10))

I'm sure the logic in this calculation can be simplified, and the E<11/E<21/E<31 calculation is performed 3 times, so if the value of E is 5 then it's less than 11, less than 21 and less than 31 so is subjected to 3 calcuations of C=round (C-(C/10)).

Sorry for a smelly one on a Sunday morning!