I had a go and did it this way, is that right?
Breakdown the brackets, starting with the brackets with the brackets ( ks / d ) / 3.7 )
We know that Ks = 1.5 x 10-6m and d= 0.04m so;
1.5 x 10-6m / 0.04 = 3.75 x10-5
= 3.75 x10-5 / 3.7 = 1.01 x10-3
= 1.01 x10-3 ^1.11 = 2.860x10-6
We now have...