Decalculator Tax vs normal tax formula

[abucady]

Greetings ,

i saw some companies use the first formula .. is it correct !

the total include tax is 24665 and the rate tax is 15% :

1- decalculator the tax from total

24665 / 1.15 =21448

24665-21448=(3217)

tax 3217.

but when you do it normally

24665*.15= 3688

thaks