Respuesta :
$6.84 divided by 18= .38 which means 38 cents per pen
$8.40 divided by 30= .28 which means 28 cents per pen
so $8.40 for 30 pens is a better deal than 18 pens for $6.84 by ten cents.
I would say 18 pens for $6.84 is a better deal because its cheaper.