Answer:
Since the above triangle is Iscocleles we can make our equation-
5x - 8 = 2x + 7
5x - 2x = 8 + 7
3x = 15
x = 5
Hope it helps
Step-by-step explanation:

To complete this equation, it is vital to know the slope. To find the slope using points, you subtract the first x from the second, and the first y from the second. This gives you a slope of 4. Then, you must follow point-slope form and choose one of the order pairs to use. You then write y then the negative of your number. Since the number is already negative, you turn it into a positive. On the other side of the "=" sign, you write your slope, 4 distributing to x. Then you write the negative of your x value. Since it is already negative, it turns into a positive. This gives you a final answer of y+1=4(x+2). I realize that this doesn't line up with your fill-in-the-blank answer, so I am sorry if it doesn't work.
C because the slope of f(x) is -2, and the slope of g(x) is -7