What is the answer of 3X plus 3X plus Y plus Y?

Answer 1

[ 3x + 3x + y + y ] isn't a question, so it doesn't need an answer.

But you can clean it up and make it shorter.

-- Remember that 3 of anything plus another 3 of the same thing is 6 of them,

so 3x + 3x = 6x .

-- Then remember that 1 of anything plus another one of the same thing is 2 of them,

so y + y = 2y .

If you use both of these facts, then your original expression is the same thing as [ 6x + 2y ].

That's not an 'answer' to anything. It's just a neater way of writing it.