Draw a mathematical tree of division and division, first convert the number of parts into numbers and then draw a picture. When a fraction is divisible by a fraction, it must be converted into a component number and multiplied by this fraction before drawing. A rectangle, 1/2 times 4/5, first draw a rectangle, color it with 1/2, then divide it into 5 parts on average and paint 4 of them. The total rectangle is divided into 10 parts on average and painted with 4 parts.