What is the word or phrase?

Why is a river so rich ?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

Can you find out the total number of triangles in the given figure?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

Why is it very easy to weigh a fish?

Do You See It?

Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

My grandson is about as many days as my son in weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 120 years. Can you tell me my age in years ?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?