# Friction is a very clever force

A particle moving on a smooth horizontal surface strikes a stationary wall. The angle of strike is equal to angle of rebound and is equal to 37 degrees.

The coefficient of restitution with the wall is
$$E=0.20$$.

If the friction coefficient between the wall and the particle is in the form of $$X/10$$. Find the sum of the first three multiples of $$X$$

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