Answer:
B and D
Explanation:
14x - 7x + 21
Simplifies into
B. 7x + 21
When you combine like terms 14x and 7x, you'll subtract 7 from 14, which gives you 7x and you add 21 just as before.
D. 7(x + 3)
When you simplify after combining like terms, you can factor. 7 is a factor in both itself and 21. So 7x / 7 = x and 21 / 7 = 3. Which gives you 7(x + 3)