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?

In a college, the ratio of foreign to local students is 3:7. If three-fourths of the local students are female...

Apu, Babu, and Tipu bought a football. Apu paid the largest amount of money, Tipu paid twice as much as Babu,...

then which of the following is correct?

When the integer n is divided by 4, the quotient is q and the remainder is 1. But when it is divided by 7, the...

x years ago, Apu was one-fifth as old as Tipu was then. Tipu will be twice as old as Apu. What is the ratio of...

A 250-meter-long train passes a person in 10 seconds, and the person was running at 5 km/h in the opposite dir...