If there are no more than 50 students in a class, there are a girls and b boys, and (4/7)a=(1/2)b is satisfied, then the maximum number of students in this class.
某班学生不超过50人，其中有女生a人，男生b人，且满足(4/7)a=(1/2)b，则这个班最多有学生多少人．
<gadget id="calculator">7 + 8</gadget>
<output>15</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<result>45</result>