Answer:
answer B
Step-by-step explanation:
hello,

so the winner is the answer B
hope this helps
Answer: 7x^2+21x+14
Step-by-step explanation:
(7x+7)(x+2)
Multiply each term in the first parentheses by each term in the second parentheses (FOIL)
7x×x+7x×2+7x+7×2
↘ ↙
7x×x calculate product
7x^2+7x×2+7x+7×2
↘ ↙
7x×2 calculate product
7x^2+14x+7x+7×2
↘↙
7×2 multiply numbers
7x^2+14x+7x+14
↘ ↙
21x collect like terms
7x^2+21x+14 is your end result.
Check out the picture I've got the full explanations on there
Hope it's clear
2.

(this is given in the first sentence)
3.

and

due to ...
7. ... the alternate interior angles theorem (which holds because

and

are parallel)
8. Because the above establishes that

, which means

, which in turn means

is a parallelogram.