Answer:
Friction Force = 17.66 N
Equation for Solving for Friction Force
Friction Force = Coefficient of Friction * Normal Force
Given
Mass = m = 12 kg
Force = 25 N ⇒ Irrelevant to this question due to forces in the x-direction canceling each other out by being equal and opposite (Newton's Third Law of Motion)
Coefficient of Friction = μ = 0.15
Solving for Normal Force
Drawing a free-body diagram would help with this problem
Normal Force = Force of Gravity due to Newton's Third Law
Normal Force = mass * gravitational constant = mg = 12 kg * 9.81 m/s^2
Normal Force = 117.72 N
Solving for Force of Friction
Friction Force = Coefficient of Friction * Normal Force = μ * N = 0.15 * 117.72 N
Friction Force = 17.66 N