2, 3, 5, 9, 17, _ What is the next number in the sequence?

What does the below mathematical rebus mean?

Solve the counting riddle by identifying the number of triangles in the given picture.

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

What is at the end of a rainbow?

When can we add 2 to 11 and get 1 as the correct answer?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?