What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

How many sides does a circle have?

John and his team plan to rob a safe. They got just one chance to break the code else the local police will be informed. Below are clues:
A) Exactly one number is perfectly placed: 9 8 1
B) Everything is incorrect: 9 2 4
C) Two numbers are part of the code of the safe but are wrongly placed: 0 9 3
D) One number is part of the code of the safe but is wrongly placed: 1 4 7
E) One number is part of the code of the safe but is wrongly placed: 7 8 3

Solve the following series:
AZ, GT, MN, __, YB

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

In an Art Gallary, When the clock hit 11 am, Artist hung the painting number 30. When it struck 4 pm, he hung painting number 240 and when it struck 7:30 pm, he hung painting number 315.

Can you determine, which painting number will he hang when the time is 9:20 pm?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.