What does kepler's first law of planetary motion imply? a. a planet moves at a constant speed at all points in its orbit. b. the distance that a planet is from the sun depends on the mass of the planet. c. uniform circular motion is adequate to describe the motion of all planets. d. the distance between the planet and the sun changes as the planet orbits the sun. e. planets closer to the sun than earth will show retrograde motion.

The first law is that planets revolve around the sun in elliptical orbits with the sun at one focus in elliptical orbits, the distance to the planet from the sun changes during the orbit, so the best answer is D.

good for her? ? where is the question?

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form