Kajol riding his bike at 24 km/h reaches his office 5 minutes late. If he would have reached the office 4 minutes earlier than the scheduled time by traveling 25% faster, how far is his office from his house in km?
The fee for a course was increased by x percent from that of the previous year. Arif, a meritorious student, got y percent waiver on his course fee for his extraordinary performance. If the fee collected from Arif is 80% of the course fee of the previous year, what is the value of yyy in terms of xxx?
A box contains 200 pens of which 25% are red and the rest are black. You sold a certain number of pens, of which 60% were black. You found that among the remaining pens, only 20% are red. How many pens did you sell?