What does this rebus riddle means ?

Replace the question mark with the number below given a simple math problem.

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

Jack and Joseph are well-known golf rivals. One Day during a match, they were level at a score of 30. Jack hit a bad shot and Joseph added 10 to his score. Joseph then hit an awesome shot and he won the game.

How ?

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

Can you replace the question mark with the correct number?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Jenifer and Jesica are having a conversation.

Jenifer: I am definitely not over 30.
Jesica: I am 28 and you are surely 5 years older to me at least.
Jenifer: No, you are at least 29.

You are told that both of them are lying throughout in the conversation. Can you find their respective ages?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?