There are 30 girls in the second class of the sixth grade, and the number of boys accounts for 40% of the whole class. How many people are there in the second class of the sixth grade? (solution by equation)
六年级二班有女生30人，男生人数占全班人数的40%．六年级二班共有多少人？(用方程解)
<result>50</result>