It is known that Class 4 has 40 students, Class 1 has 50 students, and Class 1 has 20% fewer students than Class 1. Now it is required that the number of students in Class 61 is a few percent more than that of Class 41. What is the correct formula?
已知四1班有学生40位，六1班有学生50位，四1班学生比六1班少20%．现要求六1学生数比四1班多百分之几，正确的算式是多少
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 40</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>