A hockey puck is given an initial speed of
30 m/s on a frozen pond. The puck remains
on the ice and slides 130 m before coming to
rest.
The acceleration of gravity is 9.8 m/s^2 .
What is the coefficient of friction between
the puck and the ice?

x = (v+u)(v-u)/2a
where x = distance, v = final speed, u = initial speed, a = acceleration
substituting known values:
130 = (30)*(-30)/2a
a = -900/260 = -3.46 m/s^2

f = ma
u(k)*f(normal) = m*a
u(k)*m*g = m*a
u(k) = a/g
u(k) = 3.46/9.8 = 0.35