A car takes 30 mins to travel 90 km between Shamshabad to Yadadri, then find the speed.

Hint: Time and distance of travel by the car is given, the speed can be calculated using the formula
 $ S = \dfrac{d}{T} $ where,
S = Speed
d = Distance
T = Time
For conversion, remember:
1 hour = 60 minutes
Or
60 minutes = 1 hour

Complete step-by-step answer:
Time taken to travel = 30 mins
As the speed is in km, we need to convert this time into hours (higher units) :
60 mins = 1 hour
$\Rightarrow$ 30 mins = $ \left( {\dfrac{1}{{60}} \times 30} \right)hrs $
$\Rightarrow$ 30 mins = $ \dfrac{1}{2} $ hrs.
Now, speed is defined as the distance travelled per unit time:
 $\Rightarrow S = \dfrac{d}{T} $ here,
Speed (S) = S
Distance (D) = 90 km
Time (T) = $ \dfrac{1}{2} $ hrs.
Substituting the values, we get:
 $\Rightarrow S = \dfrac{{90}}{{\left( {\dfrac{1}{2}} \right)}} $
$\Rightarrow$ S = 90 X 2
$\Rightarrow$ S = 180 km/hr
Therefore, the speed of the given car takes to travel between Shamshabad to Yadadri will be 180 km/hr

Note: We cannot find the speed in km/min, the units used both for tie and distance should be comparative.
m / s : Distance in meters and time in seconds, both are the base units of the respective quantities
km / h : Distance in kilometers and time in hours, both are equally higher units of the respective quantities.
Additional Information: We use speedometers in vehicles to measure the speed of that particular vehicle.
Speed can also be calculated using distance – time graph as speed is dependent upon both.