Mike watch 100 m north then watch 30 m south after this he walks another 10 m north what is the magnitude of his total displacement during this walk in meters

His total displacement is 80 m northwards

Explanation:

Given;

Mike's first displacement, x₁ = 100 m North

Mike's second displacement, x₂ = 30 m South

Mike's third displacement, x₃ = 10 m North

Let his Northwards direction be positive, and

his Southwards direction be negative

His total displacement = (100 m North) + ( - 30 m South) + (10 m north)

                                     = (100 m + 10m - 30 m)

                                     = 80 m  Northwards