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Science calculation

I'm getting confused about this calculation on gene cloning with BamHI endonuclease.

I have this data from where we are transforming E. coli cells. In plate 3, it is the growth of cells with uncut plasmid DNA. In plate 4, it is the growth of BamHI digested plasmid DNA with no insert DNA. In plate 5, it is the growth of self-ligated plasmid DNA. and in plate 6, it is the growth of plasmid + insert DNA ligated together. The blue colony is due to the self-ligation of plasmid and from the uncut plasmid. The white colony is recombinant cells.

Results Blue colonies / White colonies
Plate 3 3,795 0
Plate 4 378 0
Plate 5 1,730 1
Plate 6 1,636 157
What percentage of the blue colonies on plate 6 are likely to be self ligations? how do I go about doing this?

Do I first calculate the efficacy of BamHI in digesting plasmid by dividing plate 4/plate 3 x 100? and then what?

Apparently I need to find the ligase efficiency by dividing plate 5/plate 3 x 100?