Afirst class postage stamp was $0.02 in 1885. the same first class postage stamp in 2006 was $0.39. what is the percent of increase in the cost of a first class postage stamp?

How do i do this activity, is appreciated

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?

Find the equation of the ellipse with the following properties. the ellipse with foci at (0, 6) and (0, -6); y-intercepts (0, 8) and (0, -8).edit: the answer is x^2 over 28 + y^2 over 64 = 1