A rectangle has dimensions x by 2x. What is x if the perimeter of the rectangle is 48? Would it make this problem seem more relatable if we said it was a candy bar? Okay, it's a candy bar. Boom.
Perimeter is x + x + 2x + 2x = 6x. Solve the equation to get x = 8. That's how much you'll be eating if all you do is nibble around the edges.