She must sell at least 18 necklaces to have a profit of at least 1,650 . In order to pay for her monthly expenses she needs to sell at least 43 necklaces. If she wants to have 1,650 remaining after paying for her monthly expenses she'll have to sell around 61 necklaces.
On average one tank holds 108 gallons because 432.4 divided by 4 is 108.1. One half full tank would hold about 54 gallons (54.05 to be exact) because half of 108.1 gallons (a full tank) is 54.05 gallons.
