15x-10=20
+10 +10
15x=30
\15 /15
x=2
you add 10 to both -10 (they cancek eachother out) and 20 (equals 30)
Then you divide 30 by 15 (equals 2) and 15 by 15 (they cancel eachother out)
Then you get x=2
The vertex form:

(h,k) - the coordinates of the vertex

The coordinates of the vertex are
(-4,13).
Answer
D
Step by Step
8(length)x7(width)x14(height)=784 cubic inches
1a) no it would be 54
1b) yes
1c) yes
1d) no it would be 40
1e) yes
hope this helped