Newton's 3rd law- inclined plane

[mcryder16]

Homework Statement

Two packages at UPS start sliding down the 18° ramp. Package A has a mass of 5.26 kg and a coefficient of friction of 0.22. Package B has a mass of 11.67 kg and a coefficient of friction of 0.15. How long does it take package A to reach the bottom? (s=2.1 m)

Homework Equations

Any ideas of how to start this problem?

The Attempt at a Solution

 

[LowlyPion]

How would you think to start the problem?