To save for a down payment on a home, suppose you decide to invest in an annuity that pays 7.0% annual interest, compounded annually. If you contribute $8,000 every year for 5 years, how much interest would you earn during the 5 years?

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

Asap! i'm not good math and i'm lost.

Parabolas y=−2x^2 and y=2x^2+k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.