Answer
0.132 Newtons
Work Step by Step
The puck takes 15m to stop and it has an inital speed of 6 m/s. To find the acceleration during this time we can use:
$v^2 = v_{0}^2 + 2a\Delta x$
where v0 = 6, v = 0 since it is stopped and Delta x = 15m.
We find that a = -1.2 $m/s^2$.
Then since F = ma and the mass of the puck is 110g or 0.11kg then the Force acting on it (which was friction) is 0.132N.