某个班级的男女生共有 51 人，男生的<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251126/23807201_0.png">等于女生的<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251126/23807201_0_1.png">问女生有多少人？ <br/>