Explanation:
I don't know what the information below "Values:" is and means.
but we can solve this by using the given ratio :
$9 / 6 kg = 9/6 $/kg
as 6 kg cost $9.
how many kg cost $3 ?
well, what do have to multiply $9 with to get $3 ?
right, ⅓ is that factor.
to keep the overall value and information of a ratio (or any form of fraction), we need to multiply both sides (numerator and denominator) by the same factor.
so,
⅓/⅓ × 9/6 $/kg = (9/3) / (6/3) $/kg = 3/2 $/kg
as this result tells us : 2 kg cost $3.