Answer:
13 m/s east
Step-by-step explanation:
We can solve the problem by using the law of conservation of momentum, which states that the total momentum before the collision is equal to the total momentum after the collision:

where
m = 0.1 kg is the mass of each puck
u1 = +13 m/s is the initial velocity of puck 1
u2 = -18 m/s is the initial velocity of puck 2 (here I assume the west direction to be the negative direction, so I put a negative sign)
v1 = -18 m/s is the final velocity of puck 1
v2 = ? is the final velocity of puck 2
Simplifying m from the formula and substituting the data, we can find the final velocity of puck 2, v2:

And the positive sign means that puck 2 is moving east.