The answer is the option A, which is: A. x-7=x²+2x-4
The explanation is shown below:
To solve this problem you must apply the proccedure shown below:
1. You have the following system equations given in the problem above:
<span>y=x-7
y=x²+2x-4
2. Therefore, when you substitute for y in the bottom equation, you obtain:
</span>x-7=x²+2x-4
This is what I got for it if it helps
1800/3 = 600
Every pound covers 600 square feet
8400/600 = 14
<span>14/4 = 3.5 (round up) so it would become 4.
</span>
You would need 4 bags.
I hope this helps!