A sheet of paper measures 30cm by 20cm. A strip 4cm wide is cut from it all around. Find the area of the remaining sheet and also the area of the strip cut out.
the original sheet is
30*20 = 600 cm^2
the remaining sheet is
30-8 by 20-8
or 22 * 12 = 264 cm^2
so you removed:
600 - 264