The two laws that best explain how the planets are able to stay in orbit about the sun are
kepler's 1st and 2nd laws of planetary motion
kepler's law of ellipses and newton's law of inertia
newton's laws of gravity and inertia
newton's 2nd and 3rd laws of motion

Newton's laws of gravity and inertia are the two laws that best explain how the planets are able to stay in orbit about the Sun.

Kepler's Laws
1st - The orbit of the planet about the Sun is an ellipse with the Sun at one focus.
2nd - A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.
3rd - The squares of the sidereal periods of the planets are proportional to the cubes of their semimajor axes.

Newton's Laws of Motion
1st  - A body remains at rest or moves in a straight line at a constant speed unless it is acted upon by an outside force.
2nd - If a force, F, works on a body of mass M, then the acceleration, A, is given by F = MA
3rd - If one body exerts a force on a second body, the second body exerts an equal and opposite force on the first.

Ithink the answer would be 1,350!