Answer
See below
Work Step by Step
The standard form for an ellipse:
$$\frac{(x-h)^2}{b^2}+\frac{(y-k)^2}{a^2}=1$$
We know $h=3$. Use this to find h: $h=\frac{-10+6}{2}=-2$
Find c: $c=-7-k=-7-(-2)=-6$
Find b by using the formula $a^2+b^2=c^2\\b^2=a^2-c^2\\b^2=8^2-5^2=39\\b=\sqrt 39$
Substitute the values: $$\frac{(x-3)^2}{39}+\frac{(y+2)^2}{64}=1$$