You have a credit card with a balance of $2,856.74 at a 14.75% APR. You decide to put $629.63/month toward reducing your debt. How much interest do you save in 1 full month?

52 weeks in a 12-month year, then your expenses monthly expenses would be:

$954.32 * 52 / (12 * 2) = $2,067.69 and your discretionary income is $1,100.20. Your 50% savings would be $550.10 per month. Actually the year has 52 weeks and a day (365 days), so your more correct answer for expenses would be $954.32 * (365 / (14*12) = $2,073.37 and you can do the rest.

As to the C/C interest savings per month: $550.10 * 0.1475/12 = $6.76.