Answer:
AD=2
Step-by-step explanation:

Answer:
C. Reasons for changes in trends can be identified.
Step-by-step explanation:
The others would all be disadvantages.
Answer:
14a + 20
Step-by-step explanation:
8(a + 2) + 2(2 + 3a)
expand the bracket
8a + (8*2) + (2*2) + (2*3a)
8a + 16 + 4 + 6a
bring like terms together
8a + 6a + 16 + 4
14a + 20