Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 麦雅有两个姐姐。第一个姐姐的年龄是麦雅的两倍。第一个姐姐比麦雅小一岁。他们的平均年龄是5岁。麦雅多大了？


### Response:
 他们的总年龄是15，因为3 x 5 = <<3*5=15>>15岁
15 - X - 2X -(X-1) 等于 16 = 4X
麦雅是4岁，因为16 / 4 = <<16/4=4>>4岁