In step one, you are supposed to add 25 to both sides, because if you just subtract, it would be -5x-50=53
Hi there!

Find the midpoint using the midpoint formula:
m = (p1 + p2) / 2
m = (-2 + 12) / 2
m = 10 / 2
m = 5.
It’s 90 after you multiply the length, width, and height
B=x-5
To get x on its own you have to add 5 to both sides. This gives you:
b+5=x
or
x=b+5