Target Issue - Not sure if weighted target is needed

I am having an issue regarding my companies KPIs .

We have 4 lines we were running 5 days a week. We are now running 2 lines 7 days a week. My issue is the targets on these lines are in the low 50% mark. But the overall target for the plant is 55%. This would mean these lines would never reach the target.

How can I resolve this, and ensure these two days are reported correctly. (Weighted Target), not sure how to do this, or if this would resolve this.

Just to define this. We will b running the 4 lines each week. Line 9+11 will run 7 days, and other lines run 5 days. Its not fair in my eyes basing the weekend against a fixed higher target

I'm certainly no mathematician and truly have no idea what these numbers mean....but, and this is totally just something I'm throwing out there that is probably ridiculous....and I'm only doing so because no else has jumped in yet

In order to make GV9 and GV11's figures look similar to the other lines, I divided the percentage by 5 (days) and multiplied by 7 (days).
e.g. in:-
cell N5: =D18/5*7 and copy across
cell N6: =D26/5*7 and copy across

The figures look similar to the other lines, but maybe that's a complete fluke....As I stated, I really don't know what I'm saying