Answer:
£800
Explanation:
Use the percentage formula: NV = m x OV
NV is New Value;
m is Multiplier;
and OV is Old Value.
£640 in the New value, so now we have to convert 20% to a multiplier and find out the Old value.
Make OV the subject of the formula: OV = NV / m
So 20% decrease would mean: 100 - 20 = 80 * 100 = 0.80
Divide 640 (NV) by 0.80 (m) and it will give you:
£800
And it would make sense that the OV is higher, and it matches the statement -> as the NV is the decrease.