Well, split into two parts then multiply the sides and then round it to the nearest tenth.
If the area for a circle is

, you can write it in terms of its diameter like this:
Store C offers the lowest price at $94.94
The slope of the line is 50. You can try looking at the equation, which is
y=50x+500
500 is your y-intercept, and is where the cost starts.
50 is your slope, since the cost goes up by $50 every time.
x is how many hours, which determines how many $50s there are.
I hope this helps. All in all, the slope is 50.
I think its idfk…maybe?!?