1. Energy and momentum.

Mass A (m_A=1.9kg) is initially at rest, compressed against a spring for a compression of x=0.035m. It's then let go and collides with mass B (m_B=2.4kg) initially at rest) in a head-on elastic collision. Mass B then slides forward and then up a straight incline of angle 17 degrees for a distance (along the incline) of 0.89 meters maximum. What was the spring constant?

You may treat the objects as point masses. Assume all surfaces are frictionless.