The answer depends on the value of x, which is not given.
what does a40 cal. bullet look like
percentage of increase from 40 to 500 = 1150%% increase =|original value - new value|/original value * 100%= |40 - 500|/40 * 100%= 460/40 * 100%= 23/2* 100%= 1150%
9mm is cheeper cause it's a smaller round.
40
$200
Depends on the model, all have their own virtues however the best value listed is the Springfield armory XD .40 S&W.
100-450 USD
10-40 usd
100-300 USD
40-150
50-300 USD or so
50-400 usd
40 USD or so
100-400 USD
40-100 or so
100-435 USD