Originally Posted by

**Chaim** So I'm on the second part right now to find the surface area of the rectangle which is

2ab + 2bc + 2ac right?

a = 20-2x

b = 25-x

c = x

2(20-2x)(25-x) + 2(25-x)(x) + 2(20-2x)(2x)

=2(500-20x-50x+2x^2) + 2(25x+x^2) + 2(40x-4x^2)

=2(500-70x+2x^2) + 2(25x+x^2) + 2(40x-4x^2)

=1000-140x+4x^2+50x+2x^2+80x-8x^2

=1000-60x-2x^2

Though I think I messed up, it's suppose to be -50x instead of -60x, but I don't know how did I do it wrong

And how would you do "What are the explicit dimensions if the exposed surface of the area is 600 square inches?"

Also, how did you get (50-2x)/2

I understand the 50-2x, but all over the 2, how did you get that?