$A$ farmer travelled a distance of $61 \, km$ in $9 \, hours$. He travelled partly on foot at $4 \, km/h$ and partly on bicycle at $9 \, km/h$. The distance travelled on foot is (in $km$)

One third of a certain journey is covered at the rate of $25 \, km/hr$,one-fourth at the rate of $30 \, km/hr$,and the rest at $50 \, km/hr$. The average speed for the whole journey is (in $km/hr$):

$A$ and $B$ are two towns. $A$ car goes from $A$ to $B$ at a speed of $64 \, km/h$ and returns to $A$ at a slower speed. If its average speed for the whole journey is $56 \, km/h$,find its return speed (in $km/h$).

The speed of a car increases by $2\, km/h$ after every hour. If the distance travelled in the first hour was $35\, km$,what is the total distance travelled in $12$ hours? (in $km$)

$A$ train $300 \ m$ long is running with a speed of $54 \ km/h$. In what time will it cross a telephone pole? (in $seconds$)

Two stations $A$ and $B$ are $100 \, km$ apart on a straight line. One train starts from $A$ at $7 \, am$ and travels towards $B$ at $20 \, km/h$ speed. Another train starts from $B$ at $8 \, am$ and travels towards $A$ at $25 \, km/h$ speed. At what time will they meet?