Answer:
Han= 24 mins
His sister= 24 mins
His dad= 36 mins
His grandmother= 36 mins
Explanation:
The above picture shows another method to solve the question without the use of many variables. This method involves the use of units to show the duration each person spent sitting in relation to the others (except grandmother since she sat throughout). Models were drawn to help with visualization.
G stands for grandmother and H, S and D stands for Han, his Sister and his Dad respectively.