The number of fifth grade is 300, the number of fourth grade is 40% of the total number of fourth, fifth and sixth grades, and the number of sixth grade is half of the total number of fourth and fifth grades. How many people are there in the three grades?
五年级人数是300人，四年级人数是四、五、六年级总人数的40%，六年级人数是四五年级总人数的一半．问三个年级共有多少人？
<result>1_125</result>