the card has an annual percentage rate of 15%

last months balance on the card was $423.78. During the month purchases totaled $123.43. a payment of $100 was paid.

using the "unpaid balance method" what is the finance charge and what will be the the current balance.

well for the finace charge I used the last month's balance of $\displaystyle 423.78 \times \left(\frac{0.15}{12}\right)=($5.30 finance charge)$

then for the new balance.

$\displaystyle 423.78+123.42-100= 447.20$

$\displaystyle 447.20 + 5.30 = ($452.50 current balance)$

this is one of the multiple choices but wasn't sure just what balance you apply the

$\displaystyle \frac{0.15}{12}$ to?