You use the *7/47 to get the figure for VAT that is included in a gross figure: Ie £240 gross*7/47 gives you a figure of 35.74 fo the VAT included in that 240, hence net was 240-35.74=204.26
From the above posting you seam to be wanting to add VAT to a net figure? If so, the calculation would be simply 200*20/100= 40
I can't work out why you were using th *7/47 unless you had a gross figure and wanted to work out the VAT included inthat figure?