What is the lowest price per item?
$6 for 3
$9 for 6
$10 for 8
$1.40 each

For each, it's easier to find what one item costs.

$6 for 3 = 6 divide by 3 = $2 per item
$9 for 6 = 9 divide by 6 = $1.50 per item
$10 for 8 = 10 divide by 8 = $1.25 per item
$1.40 per item

The best deal for lowest price per item is the $10 for 8