根据短文内容，选择最佳答案。
Chen Hui, Zhao Mei, Li Nan and Yu Jing are good friends, but they eat different foods for lunch. Here is their lunch menu (菜单).
Name | Food | Place | Price（yuan） |
Chen Hui | rice, chicken and carrots | Meiwei Restaurant(饭店) | 12.00 |
Zhao Mei | dumplings(饺子) | Hongmao Restaurant | 14.00 |
Li Nan | a hamburger | Jiazhou Restaurant | 15.00 |
Yu Jing | tomato and egg noodles | Baixing Restaurant | 10.00 |
（
）展开式中
的系数为10，则实数a等于（ ）