Answer:
1. 65 N. 
2. 160 N. 
3. 0 N.
4. 210 N.
5. 90 N. 
Explanation:
1. Determination of the net force. 
Force applied to the right (Fᵣ) = 80 N
Force applied to the left (Fₗ) = 145 N
Net force (Fₙ) =? 
Fₙ = Fₗ – Fᵣ
Fₙ = 145 – 80
Fₙ = 65 N
Thus, the net force is 65 N 
2. Determination of the net force. 
Force 1 applied to the left (F₁) = 35 N
Force 2 applied to the left (F₂) = 125 N
Net force (Fₙ) =? 
Fₙ = F₁ + F₂
Fₙ = 35 + 125 
Fₙ = 160 N
Thus, the net force is 160 N.
3. Determination of the net force. 
Force applied to the right (Fᵣ) = 75 N
Force applied to the left (Fₗ) = 75 N
Net force (Fₙ) =? 
Fₙ = Fₗ – Fᵣ
Fₙ = 75 – 75
Fₙ = 0
Thus, the net force is 0 N
4. Determination of the net force. 
Force 1 applied to the right (F₁) = 150 N
Force 2 applied to the right (F₂) = 60 N
Net force (Fₙ) =? 
Fₙ = F₁ + F₂
Fₙ = 150 + 60 
Fₙ = 210 N
Thus, the net force is 210 N.
5. Determination of the net force. 
Force applied to the right (Fᵣ) = 115 N
Force applied to the left (Fₗ) = 25 N
Net force (Fₙ) =? 
Fₙ = Fᵣ – Fₗ 
Fₙ = 115 – 25
Fₙ = 90 N
Thus, the net force is 90 N