ABCF is a rectangle. CDEF is a trapezium. AE is a straight line. AB = 9cm, AE = 11cm and DE =5cm. The perimeter of rectangle ABCF is 28cm. Calculate the area of trapezium CDEF.

The moving of decimal to the left is a shortcut to the operation of multiplying number by decimal numbers. So the power of 10 that is involved in converting the measurements of pete is -4, so he needs to multiply the measurement by 10^-4 to convert it.