#color(blue)("Use of wording is critical")#

Note that in mathematics the word 'of ' is interpreted as multiply. Also the letter 'a' (as a word) is interpreted as 1 of #->1xx#

#color(brown)(ul("I am convinced this is NOT what you meant!"))#

A percent #-> 1/100#

Let the fraction be #x#

#" Fraction" color(white)("d")" of "color(white)("d")"a percent"#

#color(white)("ddd")xcolor(white)("dddd.d")" of "color(white)("dd") 1/100#

#color(white)("ddd")x color(white)("dddddd")xx color(white)("ddd")1/100-=0.004#

#color(white)("ddddddddddddddddddd")uarr#

#color(white)("ddddddddddddddd")obrace("equivalent to")#

#x=100xx0.004 = 0.4 ->4/10color(brown)(" ???????")#

#" Fraction" color(white)("d")" of "color(white)("d")"a percent"#

#color(white)("dddd")4/10 color(white)("dddd")xxcolor(white)("dddd")1/100color(white)("ddd") -= 0.004 #

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#color(blue)("Did you mean: in the fraction format of percentage?")#

#0.004 -=4/1000#

But we need the percentage form of this where the denominator is 100.

#
(4-:10)/(1000-:10) -= 0.4/100#