Answer:
None of those options
Step-by-step explanation:
I just did the work myself and even ran it through a calculator but the correct answer isn't one of those options. Here's my work:

I'd contact you teacher about that...it might be an error in their system (it's happened to me a few times before where the correct answer is marked as incorrect or isn't even an option)
Step-by-step explanation:
first inequality :
x + 2y ≥ 10
second inequality :
x - y ≤ -2
Answer:
The coefficient is 3.
Step-by-step explanation:
The coefficient is the number that is grouped with an unknown number represented by a letter.
You can use Heron's formula to do this
Area of triangle = sqrt[ s(s-a)(s-b)(s-c) ] where s = half the perimeter of the triangle =
1/2 * 13+5+9 = 13.5
so required area = sqrt [ (13.5)(13.5-13)(13.5-5)(13.5-9)]
= 16.1 square meters