Answer:
A. (-1 , 3)
Step-by-step explanation:
2x + y = 1
plus 3x - y = -6
------------------------------
5x = -5
x = -1
y = 1 - (2*-1) = 3
To do this problem, you will need to know the side lengths of the triangle. If you have those, just plug them in for a, b, and c and evaluate the square root.
Here is an example. If the sides are 3, 4, 5.
It would be:

The 6 is in the formula because it is the semi-perimeter (half).
15 fluid ounces.
1quart= 4 cups
2*(1/2*8 inches*4 inches)+10 inches*4 inches