Dustin says that fgh is an equilateral triangle because the sides appear to be the same length. is reasoning valid? explain

No. The word "appear" gives it away that Dustin isn't using valid reasoning. A triangle can appear as an equilateral, but if one of the sides is even a centimeter smaller or larger, that would make it not an equilateral.

The answer would he -4,-2 because the points are just on the opposite side. since the x axis is +4 it's going to he -4 and since the y axis is -2 it stays there because whaen rotated it stays in the third quadrant