$A$ train speeds past a pole in $15 \, \text{seconds}$ and speeds past a $100 \, \text{meters}$ long platform in $25 \, \text{seconds}$. Its length in meters is:

$A$ 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 $km$)

$A$ man walking at $3 \, km/h$ crosses a square field diagonally in $2 \, minutes$. The area of the field (in $m^2$) is:

Mohan walks from Tilak Nagar to Moti Nagar and back in a certain time at the rate of $3 \frac{1}{2} \, km/h$. But,if he had walked from Tilak Nagar to Moti Nagar at the rate of $3 \, km/h$ and back from Moti Nagar to Tilak Nagar at the rate of $4 \, km/h$,he would have taken $10 \, minutes$ longer. The distance between Tilak Nagar and Moti Nagar is (in $km$)

If a person walks at $14 \, km/hr$ instead of $10 \, km/hr$,he would have walked $20 \, km$ more. The actual distance travelled by him is (in $km$)

Two donkeys are standing $400 \, m$ apart. The first donkey can run at a speed of $3 \, m/s$ and the second can run at $2 \, m/s$. If both donkeys run towards each other, after how much time (in $seconds$) will they meet?