How many days in a year is ordinary interest based on?

Can someone me do math because i am having a breakdown rn because i don’t get it

Solve: 25 points find the fifth term of an increasing geometric progression if the first term is equal to 7−3 √5 and each term (starting with the second) is equal to the difference of the term following it and the term preceding it.

The formula for finding volume of a cone 1/3pi x r^2h. the volume of a cone is 300 cm^3 and the height of the cone is 10 what is the approximate radius of the cone