Estimating the maximum possible percentage error

1. The problem statement, all variables and given/known data

Hi all! Having a problem with the ending of this question and I was wondering what I needed to do from here...

The coefficient of rigidity, *n*, of a wire of length *L* and uniform diameter *d* is given by

n=AL/d^4

If *A* is a constant and the parameters *L* and *d* are known to within ± 2% of their correct values, estimate the maximum possible percentage error in the calculated value of *n*.

Here is what I have so far...

dn = dn/dL x dL + dn/dd x dd

dn = d/d^4 dL + L/d^4 dd

n = d/d^4 x ΔL + L/d^4 x Δd

n = ΔL/L + Δd/d

Where do I go from here? Any help will be greatly appreciated (Smirk)