Question 482359
(x+10)^2 * 30 = x^2 *30 + 15000 This is the equation to solve for x, the original length and width.
We can divide by 30 to simplify.
x^2 +20x+100  =  x^2 + 500
20x + 100 = 500 subtract x^2 from each side.
20x = 400 subtract 100 from each side.
x = 20, the  length and width, in cm
30cm = larger length and width.
20cm * 20cm * 30cm =  12000 cm cubed
30cm * 30cm * 30 cm = 27000 cm cubed
27000 cm cubed - 12000 cm cubed = 15000 cm cubed (check)

Cleomenius.