Multiply or divide normally. Whenever the signs are different it’s always gonna be a negative.
Its $800 because to find interest u can use the formula I=PRT p is principal which is 500 times r which is rate-15/100(=15%) times 4
so the interest is 500×15/100×4=300
then u add 300 to 500 because the interest adds more money to the loan
5.476 rounded to the hundrdths is
5.48