The double number line below shows the prices for a certain number of packs of spaghetti at a store. Which statement correctly gives and explains the price of 9 spaghetti packs? Two number lines are shown one above the other. The number line on the top is labeled and marked at 2, 4, 6, 8. On the left of this number line is written Packs of Spaghetti. The number line below it is labeled and marked at 16, 32, 48, 64. On the left of this number line is written Price of Packs in brackets dollar sign.

$18, because the price of each pack is $2
$72, because the price of each pack is $8
$80, because the price of each pack is $8
$144, because the price of each pack is $16