The sixth grade is the first volume of mathematics (write down the formula)
The shadow area accounts for 3/5 of the total area. Divide the total area into five parts on average, and the shadow area accounts for three parts, which is 3/5.
Total area 1.5 hectares, there are two ideas, 1. The shaded part is 3 copies, with a total area of 5 copies, 0.9*5/3 or 0.9/3 * 5; 2. The quantitative relationship is 3/5 of the total area = 0.9 hectares, so divide 0.9 by 3/5.