Hallo "Anonymous",
5892,44 -> 100 % ( - 20 % = 80 % = 0,8 )
P -> 80 % P = 5892,44 *80 /100 = 4713,952
oder P = 5892,44 * 0,8 = 4713,952
$${\mathtt{5\,892.44}}{\mathtt{\,\times\,}}{\mathtt{0.8}} = {\mathtt{4\,713.952}}$$
Gruß radix 
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