Peter invested a certain sum of money on simple interest whose value grew to Rs. 300 at the end of 3 years and to '400 at the end of another 5 years. What was the rate of interest in which he invested his sum?

I travel the first part of my journey at 40 km/h and the second part at 60 km/h and cover the total distance of 240 km to reach my destination in 5 hr. How long did the first part of my journey last?

A trader buys goods at a 19% discount on the label price. If he wants to make a profit of 20% after allowing a discount of 10%, by what % should his marked price be greater than the original label price?