A designer is creating various open-top boxes by cutting four equally-sized squares from the corners of a 20-cm by 30-cm sheet of cardboard, and then folding up and securing the resulting 'flaps' to be the sides of the box.

To determine the answer below, use a graph of the appropriate function plotted on your graphing calculator. For multiple answers, enter them as a list separated by commas.

Find the side length of a cutout that will achieve a volume of 300 cm3.