How many seconds will a train $60 \; m$ in length,travelling at the rate of $42 \; km/h$,take to pass another train $84 \; m$ long,proceeding in the same direction at the rate of $30 \; km/h$?

Two trains $140 \; m$ and $160 \; m$ long run at a speed of $60 \; km/hr$ and $40 \; km/hr$ respectively in opposite directions on parallel tracks. The time (in $seconds$) which they take to cross each other is:

$A$ train $110 \;m$ long is running with a speed of $60 \;km/h$. In what time (in $seconds$) will it pass a man who is running at $6 \;km/h$ in the direction opposite to that in which the train is going?

Two trains are running in opposite directions with the same speed. If the length of each train is $120 \; m$,and they cross each other in $12 \; s$,then the speed of each train is (in $km/h$):

$A$ train $75 \; m$ long overtook a person who was walking at the rate of $6 \; km/h$ and passed him in $7 \frac{1}{2}$ seconds. Subsequently,it overtook a second person,and passed him in $6 \frac{3}{4}$ seconds. At what rate (in $km/h$) was the second person travelling?

$A$ jogger running at $9 \; km/hr$ alongside a railway track is $240 \; m$ ahead of the engine of a $120 \; m$ long train running at $45 \; km/hr$ in the same direction. In how much time (in $sec$) will the train pass the jogger?