Answer
"A number decreased by 5" translates to "$x-5$"
"A number subtracted from 5" translates to "$5-x$"
Work Step by Step
Decreasing by an amount has to do with subtracting that amount (from some value)
"A number decreased by 5" means
" x decreased by 5" which also means
" 5 is subtracted from x", which we write
$x-5$
"A number subtracted from 5" means
"x subtracted from 5", which we write
$5-x$
