I have a question, assume that I have a sentence:
There are 4 balls in the box, 2 white balls and 2 black balls.
Can I omit the noun 'balls' like this for short?
There are 4 balls in the box, 2 white and 2 black.
Or in a normal conversation like this:
A: Remember to buy 4 pens when you go to the supermakert.
B: Which color do you want?
A: 2 red, 2 blue (2 red pens and 2 blue pens)