Question

How do you find the answer for 3x+(7x+10)

Answer 1

You're sitting in your room at home, and you have  '3x'  on the shelf.
Suddenly, your dog starts barking, then the front doorbell rings, and
you hear a large brown diesel truck driving away. 

Hurrying to the door, you find a small package inside the screen door,
addressed to you. You run upstairs with it, hurry to your room, close the
door, and rip the package open. 

Inside, there are two smaller boxes, each wrapped in bubble wrap.
You clear the top of your desk, carefully unwrap them, and open
each small box.

-- Inside the first one, you find  '7x' .

-- Inside the other one, you find  '10' .

You run to your shelf and get the  '3x'  that have been there for months.
You add them to the  '7x'  that just arrived.  They fit together perfectly,
and now you have  '10x'.

You still have the brand new  '10'  that has just been delivered, but it
doesn't fit together with anything else that you have.  It just has to stay
as  '10' .  Now you have  '10x + 10'  on your desk.

You put them up on your shelf, wondering what you might be able to
do with them.

A few weeks later, the answer hits you !  Valentine's Day is coming,
and you have exactly what you need to show your ten closest friends
how much you care.

With hands shaking with excitement, and beads of sweat beginning to
gleam on your fore head, you bring ten pieces of tissue and ten strips
of bright ribbon to your desk.  Then you go to your shelf and gently
bring the  '10x + 10'  over to the desk.  Now you lock your door and
go to work.

You separate the  '10x + 10'  into ten equal portions.  You carefully
wrap each portion in a wrapping of tissue, and tie each one with with
a bright bow of ribbon. 

And there you have ten identical gifts for your ten closest friends.
Each little package contains exactly the same thing inside.  When
each of your ten friends unwraps his or her special gift, each one
will find the same identical contents.  All ten of those tiny packages
were made out of that  '10x + 10'  that you kept on your shelf, and
each one holds a small, delicate  'x + 1'  there in its tissue.

Answer 2

3x + (7x + 10)
-> 3x + 7x + 10
You can't really figure out what X is since it isn't an equation (there's no equal sign)
but you can simplify this problem.
3x + 7x + 10
-> 10x +10