Tony buys a cd that is priced at $13.59. he has a coupon for $1.85 off. he pays with a $20 bill. which is the best whole number estimate of how much change he gets? $8 $8.26 $9 $9.26

I'd suggest rounding up both $13.59 and $1.85:  $14 and $2.  Subtracting the discount (~$2) from the price (~$14) results in $12.  Subtracting this discounted price from the $20 cash in hand results in change of approx. $8.

No solution : there is no number of boxes that she bought