How do you go from 98 to 720 using just one letter?

Replace the question mark with the correct number in below Picture:

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

There is a straight highway. Four different villages lie on that highway. The distance between them is different. The third village is 60km away from the first village; the fourth is 40 km away from the second; the third is 10 km near to the fourth that it is to the second.

Can you calculate the distance between the fourth and the first village ?

Find the 8 in the below-given Image.

Can you place three balls such that the equation shown in the picture holds true?

A car is crossing a 20 km-long bridge. The bridge can support at most 1500kg of weight over it. If somehow, the weight on the bridge becomes more than that, it will break.

Now, the weight of the car is exactly 1500kg. At the midway, a bird comes and sits on the roof of the car. This bird weighs exactly 200 grams.
Can you tell if the bridge breaks at this point or not?

A man has to get a fox, a chicken, and a sack of corn across a river.

He has a rowboat, and it can only carry him and one other thing.
If the fox and the chicken are left together, the fox will eat the chicken.
If the chicken and the corn are left together, the chicken will eat the corn.

How does the man do it?