A car moves at a speed of \(90\text{ km h}^{-1}.\) 

Find the distance, in \(\text{km},\) travelled by the car in \(100\) minutes.

Nina drove \(10\) minutes from her house to her workplace at an average speed of \(60 \text{ km/h}.\)

When she drove back home, she took \(10\) minutes longer.

Find Nina's average speed, in \(\text{km/h},\) on her return journey.

Four cars, \(A,B,C\) and \(D\) departed simultaneously from Sungai Buloh to four different towns.

The table shows the average speed and the distance traveled by each car.

Zailan cycles \(12\text{ km}\) in \(40\text{ minutes}.\)

Calculate the speed of his cycling.