I am supposed to make different ligations.

These are the stocks I am given:

Cut pET41a(+) DNA: 25 ng/ul
egfp insert DNA: 7 ng/ul
Uncut pET-41a(+)/EGFP recombinant plasmid DNA: 25 ng/ul

This is the ligation I am supposed to make:
Ligation #1: 1:1 molar ratio pET-41a(+) vector: egfp insert
-50 ng NcoI/NotI cut pET-41a(+) DNA _______ ul
-7 ng egfp insert DNA _____?l
-sterile dH2O _____?l
-10x ligase buffer _____ ul (final concentration will be 1X)
-DNA ligase: 1 ul

The final volume for the ligation is 20ul.
I am trying to find out how ul of the stock I am supposed to add for the cut and I am having trouble. I am using the formula C1V1=C2V2. When I solve I keep getting 40 ul but i know that's wrong.