$A$ car during its journey travels $30 \text{ minutes}$ at a speed of $40 \text{ km/h}$,another $45 \text{ minutes}$ at a speed of $60 \text{ km/h}$,and $2 \text{ hours}$ at a speed of $70 \text{ km/h}$. The average speed of the car is (in $\text{km/h}$):

Deepa drives a bike at an average speed of $30 \, km/h$ and reaches her destination in $6 \, hours$. Hema covers that same distance in $4 \, hours$. If Deepa increases her average speed by $10 \, km/h$ and Hema increases her average speed by $5 \, km/h$,then what will be the difference in time taken by them to reach their destination?

$A$ train crosses a pole in $10 \, s$ and a platform,which is $40 \%$ longer than the length of the train,in $24 \, s$. If the length of the platform is $140 \, m$,what is the speed of the train in $m/s$?

Two cars $A$ and $B$ travel from one city to another,at speeds of $72\, km/hr$ and $90\, km/hr$ respectively. If car $B$ takes $1\, hour$ less than car $A$ for the journey,what is the distance (in $km$) between the two cities?

$A$ man travelled a distance of $80 \, km$ in $7 \, h$,partly on foot at the rate of $8 \, km/h$ and partly by bicycle at $16 \, km/h$. The distance travelled on foot is (in $km$):

Train $A$ crosses a stationary Train $B$ in $50 \text{ seconds}$ and a pole in $20 \text{ seconds}$ with the same speed. The length of Train $A$ is $240 \text{ meters}$. What is the length of the stationary Train $B$ (in meters)?